RU2484078C2 - Method of producing xylene isomers (versions) - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method involves contacting starting material containing C₉ aromatic hydrocarbons on a non-sulphided catalyst having macropore volume from about 0.02 cm³/g to about 0.5 cm³/g. The catalyst has a support which is impregnated with a hydrogenation component which is a group VIB metal or oxide thereof. The support contains macroporous binder with pore size greater than 500 E and a large-pore sieve with pore size of at least 6 E, with hourly average rate of feeding the starting material of 0.1-30, pressure of 0.17-6.9 MPa or higher and temperature of 200-800°C. The invention also relates to a method of producing xylene isomers by contacting starting material which contains C₆-C₈ aromatic hydrocarbons which employs the same catalyst.

EFFECT: use of the present invention enables to overcome diffusion limitations observed when using highly active catalysts lacking such macropores.

8 cl, 20 tbl, 17 ex, 1 dwg

Description

Technical field

The invention mainly relates to methods for producing xylene isomers and, more specifically, to methods for converting aromatic hydrocarbon feeds into xylene isomers using a non-sulfidated catalyst containing a carrier impregnated with a hydrogenation component, in which the carrier comprises a macroporous binder and a sieve having medium and / or large pores.

State of the art

Hydrocarbon mixtures containing C ₈ aromatic hydrocarbons are often products of oil refining processes, including, but not limited to, catalytic reforming processes. These reformed hydrocarbon mixtures usually contain C _6-11 aromatic hydrocarbons and paraffins, most of the aromatic hydrocarbons are C _7-9 aromatic hydrocarbons. These aromatic hydrocarbons can be fractionated into their main groups, i.e., C ₆ , C ₇ , C ₈ , C ₉ , C ₁₀ and C ₁₁ aromatic hydrocarbons. The C ₈ aromatic hydrocarbon fraction typically comprises from about 10 percent by weight (% by weight) to about 30% by weight of non-aromatic hydrocarbons, based on the total weight of the C ₈ fraction. The balance of this fraction includes C ₈ aromatic hydrocarbons. The presence of ethylbenzene isomers (“EB”) and xylene isomers among C ₈ aromatic hydrocarbons, including meta-xylene (“mX”), ortho-xylene (“oX”) and para-xylene (“pX”), is common. Together, xylene and ethylbenzene isomers are collectively referred to in the prior art and in this application as “C ₈ aromatic hydrocarbons. Usually, when ethylbenzene is present among C ₈ aromatic hydrocarbons, it is in a concentration of from about 15% to about 20% by weight. wt., based on the total weight of aromatic C ₈ hydrocarbons, with the balance (e.g., up to about 100% wt.), representing a mixture of xylene isomers. The three xylene isomers typically comprise the remaining aromatic C ₈ hydrocarbons, and especially are present in an equilibrium weight ratio of approximately 1: 2: 1 (oX: mX: pX). Thus, the term “equilibrium mixture of xylene isomers” refers here to a mixture containing isomers in a weight ratio of approximately 1: 2: 1 ( oX: mX: pX).

The product (or reforming product) of the catalytic reforming process includes C _6-12 aromatic hydrocarbons (including benzene, toluene and C ₈ aromatic hydrocarbons, collectively referred to as "BTX"). Process by-products include hydrogen, light gas, paraffins, naphthenes, and heavy C ₉₊ aromatic hydrocarbons. The BTX present in the reformate product (especially toluene, ethylbenzene and xylene) is known to be suitable gasoline additives. However, due to concern for the environment and health, the maximum allowable level for certain aromatic hydrocarbons (especially benzene) in gasoline has been significantly reduced. However, the components of the BTX can be separated in typical hydrocarbon processing processes for use in other production capabilities. Alternatively, benzene can be separated from BTX and the resulting mixture of toluene and C ₈ aromatics can be used, for example, as additives, to increase the octane number of gasoline.

Benzene and xylenes (especially para-xylene) may be more cost effective than toluene because of their suitability for other products. For example, benzene can be used to produce styrene, cumene and cyclohexane. Benzene is also suitable for the production of rubbers, lubricants, paints, detergents, medicines and pesticides. Among the C ₈ aromatic hydrocarbons, ethylbenzene is mainly suitable in the production of styrene, while ethylbenzene is a reaction product of ethylene and benzene. However, due to purity problems, ethylbenzene, which is present in the C ₈ aromatic hydrocarbon fraction, cannot actually be used to produce styrene. Meta-xylene is suitable for the production of isophthalic acid, which is directly suitable for the production of special polyester fibers, paints and resins. Ortho-xylene is suitable for the production of phthalic anhydride, which is directly suitable for the production of phthalate-based plasticizers. Para-xylene is a feed suitable for the production of terephthalic acids and esters, which are used to produce polymers such as poly (butene terephthalate), poly (ethylene terephthalate) and poly (propylene terephthalate). While ethylbenzene, meta-xylene and ortho-xylene are useful raw materials, the requirements for these chemicals and materials derived from them are not as stringent as the requirements for para-xylene and materials derived from para-xylene.

In view of the higher ratings of benzene, C ₈ aromatic hydrocarbons and products derived from them, processes were developed for the dealkylation of toluene to benzene, the disproportionation of toluene to benzene and C ₈ aromatic hydrocarbons, and the transalkylation of toluene and C ₉₊ aromatic hydrocarbons to C ₈ aromatic hydrocarbons. These processes are mainly described in Kirk Othmer's Encyclopedia of Encyclopedia of Chemical Technology, 4 ^th Ed., Supplement Volume, pp. 831-863 (John Wiley & Sons, New York, 1998), the disclosure of which is incorporated herein by reference.

Specifically, toluene disproportionation (“TDP”) is a catalytic process in which two moles of toluene are converted to one mole of xylene and one mole of benzene, such as:

Other methyl disproportionation reactions include a catalytic process in which two moles of a C ₉ aromatic hydrocarbon are converted to one mole of toluene and heavier hydrocarbon components (i.e., C ₁₀₊ heavy hydrocarbons), such as:

Toluene transalkylation is a reaction between one mole of toluene and one mole of C ₉ aromatic hydrocarbon (or higher aromatic hydrocarbon) to produce two moles of xylene, for example, as:

Other transalkylation reactions using C ₉ aromatic hydrocarbons (or higher aromatic hydrocarbons) include a reaction with benzene to produce toluene and xylene, for example, as:

As can be seen from the description of the previous reactions, methyl and ethyl groups associated with C ₉ aromatic hydrocarbons and xylene molecules, as shown, can be found attached to any acceptable carbon atoms forming a ring to form various isomeric configurations of the molecule. Mixtures of xylene isomers can then be separated into their constituent isomers in hydrocarbon processing processes. After separation, the isomers can then be processed (for example, isomerized, isolated and recycled), for example, to obtain substantially pure para-xylene.

In theory and in view of the description of the previous reactions, a mixture of C ₉ aromatic hydrocarbons can be converted to xylene and / or benzene isomers. Xylene isomers can be separated from benzene, for example, by fractional distillation.

Previously, those skilled in the art of disproportionation and transalkylation reaction technology would carry out the above reactions with a catalyst, depending on which aromatic hydrocarbon would ultimately be obtained. For example, US 5907074; 5,866,741; 5866742 and 5804059, each from Phillips Company ("Phillips"), mainly disclose disproportionation and transalkylation reactions in which a specific liquid feed containing C ₉₊ aromatic hydrocarbons is converted to BTX. Although the patents claim that the source of the liquid feed is not critical, each reflects a strong preference for the liquid feed obtained from the heavy fraction of the product obtained by the aromatization reaction of hydrocarbons (especially gasoline), which is usually carried out in a catalytic cracking unit with a fluidized catalyst ("FCC" . Low-quality liquid raw materials, including large (or long) hydrocarbons, are evaporated in an FCC unit and, in the presence of an appropriate catalyst, are cracked to light molecules capable of forming products that can be mixed with high-quality diesel fuel and high-octane gasoline. FCC plant by-products include a low-quality heavy liquid fraction which constitutes a liquid feed, preferably according to the disclosure of these patents. The present source of the preferred liquid feed proposes that the feed include sulfur-containing compounds, paraffins, olefins, naphthenes and polycyclic aromatic compounds (“polyaromatic hydrocarbons”).

According to US Pat. No. 5,907,074, BTX is generally substantially absent in the feed preferable in this patent and, therefore, no significant BTX transalkylation occurs as a side reaction with the major disproportionation and transalkylation reactions. The main reactions described in this patent occur in the presence of a hydrogen-containing liquid and a catalyst including a Y-type zeolite promoted with a metal oxide having an activity modifier incorporated therein (i.e., sulfur, silicon, phosphorus, boron, magnesium, tin oxides, titanium, zirconium, germanium, indium, lanthanum, cesium and combinations of two or more thereof). The activity modifier helps to combat the decontamination effect (or toxic effect) that sulfur-containing compounds have on metal oxide-impregnated catalysts.

According to US patents 5866741, 5866742 and 5804059, BTX is generally absent in the raw materials preferred in these patents, and therefore, no significant BTX transalkylation occurs as a side reaction with the main disproportionation and transalkylation reactions. However, BTX may be present if alkylation of such C ₉₊ chemicals with aromatic hydrocarbons is secondarily desired. According to US Pat. No. 5,866,741, these main and side reactions occur in the presence of a hydrogen containing liquid and a catalyst including a beta type zeolite having an activity promoter incorporated therein (e.g., molybdenum, lanthanum and their oxides). According to US Pat. No. 5,866,742, the main and side reactions occur in the presence of a hydrogen-containing liquid and a catalyst including a beta type zeolite having a metal carbide embedded therein. According to the '059 patent, the main and side reactions occur in the presence of a hydrogen-containing liquid and a catalyst including a zeolite promoted with a metal oxide such as mordenite.

The purpose underlying the disclosure of each of the preceding patents is the conversion of C ₉₊ aromatic hydrocarbons to BTX. Pointing to this goal, patents disclose a specific combination of liquid feed, catalysts, and reaction conditions appropriate to obtain BTX. These patents, however, do not disclose or teach how to obtain any single component of BTX (not to mention xylene isomers) for the ultimate reduction of other components of BTX. With respect to each of them, the presence of sulfur in the liquid feed is harmful for converting the metal or metal oxide in the catalyst into metal sulfide over time. Metallic sulfides have a much lower hydrogenation activity than metallic oxides, and therefore sulfur poisons the activity of the catalyst. In addition, the presence of olefins, paraffins and polyaromatic hydrocarbons in the feed quickly deactivates the catalyst, and they are converted to undesirable light gas.

Unlike previous patents, Application US 2003/0181774 A1 (Kong et al.) Discloses a method for transalkylating the catalytic conversion of benzene and C ₉₊ aromatic hydrocarbons to toluene and C ₈ aromatic hydrocarbons. According to Kong et al., The process should be carried out in the presence of hydrogen in a gas-solid phase in a fixed bed reactor filled with a transalkylation catalyst containing H - zeolite and molybdenum. The stated goal in the methods of Kong and others is to maximize the production of toluene for subsequent use as raw materials in hydrocarbon processing in a selective disproportionation reactor, and to use the obtained by-products of C ₈ aromatic hydrocarbons as raw materials in the isomerization reactor in hydrocarbon processing processes. By selective disproportionation of toluene to para-xylene, Kong et al. Propose ultimately converting a mixture of benzene and C ₉₊ aromatic hydrocarbons into para-xylene. However, such a proposal disadvantageously requires a plurality of reaction vessels (e.g., a transalkylation reactor and a disproportionation reactor) and, most importantly, does not disclose how to increase the number of xylene isomers resulting from the transalkylation reaction, while the production of toluene and ethylbenzene is simultaneously reduced.

US 2003/0130549 A1 (Xie et al.) Discloses a process for the selective disproportionation of toluene to produce a stream of benzene and para-xylene rich xylene and transalkylation of a mixture of toluene and C ₉₊ aromatic hydrocarbons to produce xylene and benzene isomers. According to Xie et al., Various reactions are carried out in the presence of hydrogen in separate reactors, each of which contains an appropriate catalyst (i.e., ZSM-5 catalyst for selective disproportionation and mordenite MSM-22 or beta type zeolite for transalkylation). Hydrocarbon processing processes are used to produce para-xylene from the resulting xylene isomers. The method disclosed by Xie et al. Assumes that large volumes of benzene and ethylbenzene are prepared as desired. Xie et al., However, do not suggest how to maximize the amount of xylene isomers resulting from the transalkylation reaction, while simultaneously reducing the production of benzene and ethylbenzene.

US 2001/0014645 A1 (Ishikawa et al.) Discloses a method for disproportioning C ₉₊ aromatic hydrocarbons to toluene, and transalkylating C ₉₊ aromatic hydrocarbons and benzene to toluene and C ₈ aromatic hydrocarbons for use as a gasoline additive. The use of benzene as a reagent in the transalkylation reaction determines the attempt by Ishikawa et al. To free low-quality gasoline fractions from benzene. Given the declared use and proposal, in order to free gasoline from benzene, a person skilled in this technology may wish that ethylbenzene in C ₈ aromatic hydrocarbons would maximize gasoline yields. In addition, a qualified person will take precautions to ensure that the resulting ethylbenzene is not inadvertently broken down to benzene - which is sought to be removed from gasoline fractions. The disclosed reactions are carried out in the presence of hydrogen and large pore zeolite, impregnated with a metal of group VIB and preferably sulfidated. In general, portions of benzene and C ₉₊ aromatic hydrocarbons are converted in the product stream, mainly including BTX. Benzene is removed from the BTX product stream and recycled back to the feed. Ultimately, toluene and C ₈ aromatics are derived from benzene / C ₉₊ aromatics. The transalkylation reaction is carried out with a large molar excess of benzene to C ₉₊ aromatic hydrocarbons (i.e., between 5: 1 to 20: 1) to obtain toluene and C ₈ aromatic hydrocarbons (including ethylbenzene). Ishikawa et al., However, do not suggest how to maximize the amount of xylene isomers obtained in the transalkylation reaction, while also reducing the production of toluene, benzene, and C ₁₀ aromatic hydrocarbons to the limit.

Previous publications do not disclose or teach or suggest to a person skilled in the art how to maximize the production of xylene isomers from aromatic hydrocarbons, reducing to a maximum the production of other BTX components, non-aromatic hydrocarbons and heavy hydrocarbons. In addition, the prior art does not disclose or teach or offer a qualified specialist a highly active catalyst suitable for the conversion of aromatic hydrocarbon feeds to xylene isomers. The catalyst disclosed in each of the previous publications is specifically selected for the conversion of a particular feed to a specific end product. There are many competent assumptions for the design of a catalyst suitable for the conversion of a particular feed to a specific end product. Among these statements are the desired activity, (form) selectivity and diffusion limitations that arise from activity and selectivity. A highly active catalyst is desirable to maximize the conversion of the feed, and selectivity is desirable to obtain a product containing certain molecules to limit other molecules to a maximum, and to purify molecules containing the conversion product (i.e., to decompose or separate unwanted molecules in the product from certain molecules that will diffuse through the catalyst). The conversion often includes by-products that are undesirable due to a number of reasons. For example, certain by-products can be very reactive and can undesirably interact with and convert the desired product into other (less desirable) molecules.

International publication WO 04/056475 generally discloses the catalytic conversion of ethylene and benzene to ethylbenzene and undesirable products such as low molecular weight products (e.g. ethylene), biphenylethanes and polyethylbenzenes. When ethyl groups (and higher alkyl groups) are separated from aromatic compounds, they exist as ethylene groups (and higher alkylene groups), which are very reactive and form undesirable by-products. For example, free ethylene groups in the mixture will react with other parts of benzene to produce biphenylethanes and polyethylbenzenes. The yield of these unwanted by-products, according to this publication, is extremely reduced on a specially designed catalyst, which includes a carrier formed from a zeolite with a large pore size and an inorganic binder. The carrier is formed using a blowing agent to include mesopores and macropores, and has a pore volume of at least 0.7 cubic centimeters per gram. Large pores and pore volumes are claimed in this application to improve the diffusion characteristics of the catalyst. Improved diffusion provides faster reagent consumption and shorter residence times, which in turn lead to lower likelihood and reduced ability of very reactive ethylene to form unwanted by-products. In addition, large pores and pore volume are also claimed in this application to improve the diffusion ability of the large polyethylated aromatic molecules that are present in these reactions.

The diffusion restrictions referred to in WO 04/056475 are, of course, peculiar to the specific conversion described therein. Even if a highly active catalyst were available for the conversion of aromatic hydrocarbon feeds to xylene isomers, those special diffusion restrictions would not be expected with such a conversion. In addition, the use of a carrier with large pores or a pore volume, such as that disclosed in this publication, would not be expected to facilitate demethylation, methyl disproportionation and methyl transalkylation reactions, because methyl groups are not even nearly as reactive as olefins ( for example, ethylene), usually do not exist as a gas in these reactions, and do not react with BTX and C ₉₊ aromatic hydrocarbons in the same way as ethylene and higher alkylenes react. Methyl groups are chemically slow reactants, and therefore, diffusion problems would not be expected by those skilled in the art as in the presence of olefins. Indeed, since the demethylation, methyl disproportionation and methyl transalkylation reactions are slow relative to the rate at which the molecules diffuse, one skilled in the art would not consider a catalyst support with such a large pore volume and such large pores to be particularly advantageous for these reactions.

The prior art does not disclose or teach or indicate to a qualified person that a highly active catalyst is suitable for the conversion of aromatic hydrocarbon feed materials to xylene isomers. Moreover, the prior art does not disclose, teaches or determines the reaction conditions under which such catalytic conversion must be carried out in order to maximize the yield of xylene isomers. In the absence of such disclosure and teachings in the prior art, it is not surprising that significant diffusion limitations are not associated with the conversion of aromatic hydrocarbon-containing feeds to xylene isomers.

SUMMARY OF THE INVENTION

It has been found that the use of a bifunctional catalyst containing macropores provides a surprising advantage in terms of, for example, improved activity (improved conversion of aromatic hydrocarbon containing feeds) without compromising selectivity for xylene, improved catalyst stability, and the ability to convert raw materials containing some non-aromatic hydrocarbons and C ₁₀₊ aromatic hydrocarbons, without catalyst deactivation, the ability to obtain very pure benzene, increase in the yield of xylene separation at the installation of the para-xylene processing process and unexpected flexibility to accommodate a variety of raw material processes using the same general process scheme and isolation of the selected conversion products as specified.

Accordingly, the present invention discloses methods for producing xylene isomers using such catalysts. In one embodiment, the method comprises contacting a feed containing C ₉ aromatic hydrocarbons with a non-sulfidated catalyst under conditions suitable for converting the feed to a product containing xylene isomers. The catalyst includes a carrier impregnated with a hydrogenation component, and the carrier includes a macroporous binder and a large pore sieve.

In another embodiment, the method comprises contacting a feed at a feed containing C ₆ -C ₈ aromatic hydrocarbons and substantially free of C ₉₊ aromatic hydrocarbons on a non-sulfidated catalyst under conditions suitable for converting the feed to a product containing xylene isomers. The catalyst includes a carrier impregnated with a hydrogenation component, and the carrier includes a macroporous binder and a sieve selected from the group consisting of a sieve with an average pore size, a sieve with a large pore size and mixtures thereof.

Additional features may become apparent to those skilled in the art from the following detailed description, taken in conjunction with the accompanying drawings, examples, and the attached claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the invention, references should be made to the following detailed description and a single drawing, basically explaining a process diagram suitable for implementing the disclosed methods and their embodiments. While the disclosed methods are subject to various forms of embodiments, the drawing illustrates (and will later describe) specific embodiments of the methods with the understanding that the disclosure is intended to be illustrative, and is not intended to limit the scope of the methods to the specific embodiments described and explained in this application.

DETAILED DESCRIPTION OF THE INVENTION

The invention mainly relates to methods for producing xylene isomers, which are particularly suitable as a chemical feedstock for producing para-xylene. Application US 10 / 794,932, filed March 4, 2004, describes a great advantage in the conversion of aromatic hydrocarbon-containing feeds to xylene isomers using a non-sulfidated catalyst containing a hydrogenation component. It has been found that the full advantage of that conversion may not actually be feasible on a commercial scale of production due to diffusion limitations encountered on a scale where the catalyst is in the form of an extruded tablet / particle. For example, a carrier impregnated with a hydrogenation component, such as a Group VIB metal oxide, where the carrier is made of a binder and a large pore sieve, has been found to be so active with respect to the conversion of a feed containing C ₉ aromatic hydrocarbons, benzene, toluene, or mixtures thereof, into a product containing xylene isomers that significant portions of the active sites within the extruded form of the catalyst are underused or not used at all. This is a diffusion limitation, and it is undesirable because significant volumes of a commercial industrial reactor will be unnecessarily occupied by a catalyst (with a lack of macropores) whose active centers cannot be used (or will not be used enough).

This diffusion limitation can be removed by reducing the feed rate to the reactor (to comply with the conversion rate); however, this is likely to lower the performance of the method. Alternatively, the restriction can be removed while maintaining the feed rate, but increasing the volume of the reactor and the amount of catalyst filling this volume (to comply with the conversion rate); however, this will likely increase capital costs.

It was very unexpectedly found that the diffusion limitation can be removed using a catalyst (carrier), which contains macropores. With a macroporous catalyst, the feed can be introduced into the reactor and diffused through the macropores to active centers in a sieve previously underused (or not used at all). The presence of macropores in the catalyst effectively increases the rate of catalytic conversion to better comply with the residence time of the feed and conversion product in the reactor. Thus, it was found that, while using an extruded form of a metal impregnated catalyst carrier with a lack of macropores, it is possible to convert aromatic hydrocarbon containing feeds to xylene isomers, using an extruded form of a catalyst containing macropores, the conversion is carried out more efficiently on a commercial industrial scale production based on a given reactor volume. In addition, the volume of the reactor requires an increase as a result of the increased feed rate in order to achieve such an effective conversion.

The use of a catalyst containing macropores is counterintuitive because the molecules of the feed, recycle and product are usually small enough to diffuse through the pores of the catalyst, with a lack of macropores. Therefore, a specialist qualified in this technology could not have suggested the use of a catalyst containing macropores to achieve conversion. In addition, in the absence of a hydrogenation component, the catalytic conversion rate would not exceed the rate at which the feed passes through the catalyst. Consequently, all active sites on the catalyst would be available raw materials (that is, there would be (or few) underutilized sites there). Thus, it was found in this application that the great advantage of a highly active, bifunctional catalyst can be higher and more realized on an industrial scale, if the extruded form of the catalyst (carrier) includes macropores.

As described in more detail below, xylene isomers can be obtained from various raw materials, which may include C ₉ aromatic hydrocarbons, toluene, benzene, and mixtures thereof. Some reactions with this feed, such as, for example, the disproportionation of toluene and the transalkylation of toluene, have been described above. In general, the methods disclosed herein include contacting the feed with a catalyst under conditions suitable for converting the feed to a product that includes xylene isomers.

The catalyst includes a carrier impregnated with a hydrogenation component. The carrier includes a macroporous binder and a sieve selected from the group consisting of medium-sized sieves, large pore sieves and mixtures thereof. The selection of sieves is based on the composition of the raw materials. For example, sieves with a large pore size should be used for raw materials containing C ₉ aromatic hydrocarbons, while sieves with an average pore size or mixtures of such sieves can be used for raw materials containing aromatic hydrocarbons containing only molecules smaller in size than C aromatic hydrocarbons ₉ , or comprising aromatic hydrocarbons, a feedstock substantially free of molecules having a size equal to or greater than C ₉ aromatic hydrocarbons. Although the disclosed methods ultimately produce xylene isomers, it can easily be understood that competing reactions will produce aromatic hydrocarbons as a by-product (for example, aromatic hydrocarbons other than xylene isomers such as benzene) in addition to the desired xylene isomers. These by-products can be beneficial, however, the amount of these by-products is preferably reduced to the limit. Therefore, in certain embodiments, a “product” can more accurately be considered an “intermediate product” because it also contains aromatic hydrocarbons as a by-product. The methods, therefore, may also include the separation of at least part of the xylene isomers from the intermediate product, to obtain an intermediate product depleted in xylene isomers, and its recycling in the feed.

Raw materials suitable for use in accordance with the disclosed methods include ultimately raw materials obtained from oil refining processes. As a rule, crude oil is desalinated and then distilled into various products. The desalination step mainly allows the removal of metals and suspended solids that could cause catalyst deactivation in further hydrocarbon processing processes. The product obtained in the desalination step is subsequently subjected to distillation under atmospheric pressure or in vacuum. Among the fractions obtained by atmospheric distillation are the crude gasoline-naphtha fraction, direct distillation naphtha, kerosene, middle distillates, gas oil, lubricating oil distillates and heavy sludge, which are often further distilled using vacuum distillation methods. Many of these fractions can be sold as final products or can be further refined in hydrocarbon processing processes that contribute to changing the molecular structure of hydrocarbon molecules or breaking them down to smaller molecules, or combining them to form a larger, more significant molecule, or transforming them into larger ones molecules. For example, the crude gasoline-naphtha fraction or direct distillation naphtha obtained in the distillation stage can be sent with hydrogen to a hydrogenation unit in which any residual olefins are converted to paraffins and impurities such as sulfur, nitrogen, oxygen, halide compounds are removed , heteroatoms and metallic impurities that can deactivate catalysts in the further processing of hydrocarbons. At the outlet of the hydrogenation unit, there is a processed depleted naphtha fraction or a substantially impurity-free hydrogen-rich gas and streams containing hydrogen sulfide and ammonia. Light hydrocarbons are sent to the reforming stage (“reforming unit”) in order to convert those hydrocarbons (for example, non-aromatic hydrocarbons) into hydrocarbons having better gasoline properties (for example, aromatic hydrocarbons). The processed naphtha, mainly comprising aromatic hydrocarbons (usually within the boiling range of C _6-10 aromatic hydrocarbons), can serve as a feed suitable for conversion in accordance with the disclosed methods of the invention.

Alternatively, a feed containing medium distillates and / or light diesel fuel can be sent to the hydrocracker and converted to a light hydrocarbon having insufficient properties for gasoline (i.e., naphtha) and sulfur (a little) or olefins. Light hydrocarbons are then sent to a reformer to convert these hydrocarbons into hydrocarbons having better gasoline properties (e.g., aromatic hydrocarbons).

At the outlet of the reformer, there is a reformate product that is substantially free of sulfur and olefins and includes not only aromatic hydrocarbons (usually within the boiling range of C _6-10 aromatic hydrocarbons), but also paraffins and polyaromatic hydrocarbons. Thus, in the next step, paraffins and polyaromatic hydrocarbons are recovered to obtain a product stream containing C ₉ aromatic hydrocarbons. Such a product stream may serve as a feed suitable for conversion in accordance with the disclosed methods of the invention.

The composition of the crude oil can vary significantly depending on its source. In addition, raw materials suitable for use in accordance with the methods of the invention disclosed in this application are usually obtained as a variety of previous oil production processes, of course, it can vary depending on the reagents / materials supplied to those oil production processes. Often, the source of those reagents / materials will dictate the composition of the feed obtained as a product of previous oil production operations. As described in more detail below, there are generally two types of feed that can be converted to xylene isomers by the methods of the invention: one that contains C ₉ aromatic hydrocarbons and one that contains benzene and / or toluene, which is substantially free of aromatic hydrocarbons C ₉ and molecules larger than C ₉ aromatic hydrocarbons.

As used herein, the term “aromatic” defines a major group of unsaturated cyclic hydrocarbons containing one or more rings represented by benzene. See mainly, “Hawley's Condensed Chemical Dictionary,” at p. 92 (13 ^th Ed., 1997). In general, aromatic hydrocarbons C _n refer to aromatic compounds having n carbon atoms. In addition, C _{n +} aromatic hydrocarbons belong to aromatic compounds having at least n carbon atoms. Thus, as used herein, the term “C ₉ aromatic hydrocarbons” means a mixture that includes any aromatic compound having nine carbon atoms. Preferably, C ₉ aromatic hydrocarbons include 1,2,4 trimethylbenzene (pseudocumene), 1,2,3-trimethylbenzene (hemimellitol), 1,3,5-trimethylbenzene (mesitylene), meta-methylethylbenzene, ortho-methylethylbenzene, para-methylethylbenzene , isopropylbenzene and n-propylbenzene. As used herein, “C ₉₊ aromatic hydrocarbons” means a mixture that includes any aromatic compound having at least nine carbon atoms, such as, for example, C ₁₀ aromatic hydrocarbons. Similarly, “C ₁₀₊ aromatic hydrocarbons” means a mixture that includes any aromatic compound having at least ten carbon atoms.

Along with raw materials including C ₉ aromatic hydrocarbons, the raw materials will usually include numerous other hydrocarbons, many of which are only present in trace amounts. For example, the feed is preferably substantially free of non-aromatic hydrocarbons, such as, for example, paraffins and olefins. A feed that is substantially free of non-aromatic hydrocarbons preferably includes less than about 5% by weight of non-aromatic hydrocarbons, and more preferably less than about 3% by weight of non-aromatic hydrocarbons, based on the total weight of the feed. Although a suitable feed is preferably substantially free of non-aromatic hydrocarbons, a feed containing non-aromatic hydrocarbons can be processed by the methods disclosed as shown in the examples below.

The feed should be substantially free of sulfur (e.g. elemental sulfur and sulfur-containing hydrocarbons and non-hydrocarbons). A feed that is substantially sulfur free preferably includes less than about 1% by weight. sulfur, more preferably less than about 0.1% weight. sulfur, and even more preferably less than about 0.01% by weight. sulfur, calculated on the total weight of the raw materials.

In various preferred embodiments, the feed is substantially free of isomers of xylene, toluene, ethylbenzene and / or benzene. A feed that is substantially free of xylene isomers preferably includes less than about 3% by weight of xylene isomers, and more preferably less than about 1% by weight of xylene isomers, based on the total weight of the feed. A feed that is substantially free of toluene preferably includes less than about 5% by weight of toluene, and more preferably less than about 3% by weight of toluene, based on the total feed weight. A feed that is substantially free of ethylbenzene preferably includes less than about 5% by weight of ethylbenzene, and more preferably less than about 3% by weight of ethylbenzene, based on the total feed weight.

In other embodiments, however, the feed may include significant amounts of one or both of toluene and benzene. For example, in certain embodiments, the feed can include up to about 50% by weight of toluene, based on the total weight of the feed. Preferably, however, the feed comprises less than about 50% by weight of toluene, more preferably less than about 40% by weight of toluene, even more preferably less than about 30% by weight of toluene, and most preferably less than about 20% by weight of toluene, based on the total weight of the raw materials. Similarly, in certain embodiments, the feed can include up to about 30% by weight of benzene, based on the total weight of the feed. Preferably, however, the feed comprises less than about 30% by weight of benzene, and more preferably less than about 20% by weight of benzene, based on the total weight of the feed.

Moreover, in various embodiments, the feed can be substantially free of C ₁₀₊ aromatic hydrocarbons. The feed, however, should be substantially free of C ₁₀₊ aromatic hydrocarbons. In general, C ₁₀₊ aromatic hydrocarbons (“A ₁₀₊ ”) will include benzenes having one or more hydrocarbon functional groups, which together have four or more carbon atoms. Examples of such C ₁₀₊ aromatic hydrocarbons include, but are not limited to, C ₁₀ aromatic hydrocarbons (“A ₁₀ ”) such as butylbenzene (including isobutylbenzene and tert-butylbenzene), diethylbenzene, methylpropylbenzene, dimethylethylbenzene, tetramethylbenzene and C ₁₁ aromatic hydrocarbons, such as trimethylethylbenzene and ethylpropylbenzene, for example. Examples of C ₁₀₊ aromatic hydrocarbons may also include naphthalene and methylnaphthalene. A feed that is substantially free of C ₁₀₊ aromatic hydrocarbons preferably includes less than about 5% by weight of C ₁₀₊ aromatic hydrocarbons, and more preferably less than about 3% by weight of C ₁₀₊ aromatic hydrocarbons, based on the total weight of raw materials.

As used herein, the term “C ₈ aromatic hydrocarbons” means a mixture containing predominantly xylene and ethylbenzene isomers. On the contrary, the term "xylene isomers", as used in this application, means a mixture containing meta-, ortho- and para-xylene, where the mixture is essentially free of ethylbenzene. Preferably, such a mixture contains less than three percent by weight of ethylbenzene, based on the total weight of the xylene and ethylbenzene isomers. More preferably, however, such a mixture contains less than one percent by weight of ethylbenzene.

A second type of feed that can be converted to xylene isomers by the method of the invention is that feed that contains molecules (e.g., toluene) smaller than the C ₉₊ aromatic hydrocarbons discussed above, that is, includes a feed containing aromatic hydrocarbons essentially free of molecules having a size equal to or greater than C ₉₊ aromatic hydrocarbons. Typically, the feed will be rich in toluene and thus will contain at least about 90% by weight of toluene, preferably about 95% by weight of toluene, and more preferably about 97% by weight of toluene, based on the total weight of the feed. This feed can mainly be converted to xylene isomers by disproportioning toluene on catalytic sieves having smaller pores than the catalytic sieves necessary for the conversion of the feed containing C ₉₊ aromatic hydrocarbons discussed above. Typically, a feed that is substantially free of C ₉ aromatics preferably comprises less than about 5% by weight of C ₉ aromatics, more preferably less than about 3 wt.% C ₉ aromatics, and extremely preferably less than about 1% by weight of C ₉ aromatic hydrocarbons, based on the total weight of the feed. This feed should also be substantially free of C ₁₀₊ aromatic hydrocarbons. A feed that is substantially free of C ₁₀₊ aromatic hydrocarbons preferably includes less than about 5% by weight of C ₁₀₊ aromatic hydrocarbons, more preferably less than about 3% by weight of C ₁₀₊ aromatic hydrocarbons, and extremely preferably less than approximately 1% by weight of C ₁₀₊ aromatic hydrocarbons, based on the total weight of the feed. The presence of C ₉ aromatic hydrocarbons and C ₁₀₊ aromatic hydrocarbons in the feed would limit the ability to use catalytic sieves with smaller pores because these molecules would not be able to pass through the sieve and ultimately clog it, rendering the catalytic material less useful or even useless condition. Therefore, for the advantageous use of catalytic sieves with smaller pores (for example, sieves with an average pore size), the feed should essentially be free of these larger molecules.

Like raw materials containing C ₉ aromatic hydrocarbons, a raw material that is substantially free of C ₉ aromatic hydrocarbons for use in accordance with the disclosed methods will typically include numerous other hydrocarbons, many of which are present only in trace amounts. For example, the feed should be substantially free of non-aromatic hydrocarbons, such as, for example, paraffins and olefins. A feed that is substantially free of non-aromatic hydrocarbons preferably includes less than about 5% by weight of non-aromatic hydrocarbons, and more preferably less than about 1% by weight of non-aromatic hydrocarbons, based on the total weight of the feed. Although the corresponding feed is preferably substantially free of non-aromatic hydrocarbons, the feed containing non-aromatic hydrocarbons can be processed by the methods disclosed herein, as demonstrated in the examples that are presented below. The feed should be substantially free of sulfur (e.g. elemental sulfur and sulfur-containing hydrocarbons and non-hydrocarbons). A feed that is substantially free of sulfur preferably includes less than about 1% by weight of sulfur, more preferably less than about 0.1% by weight of sulfur, and even more preferably less than about 0.01% by weight of sulfur, based on the total weight of raw materials.

In various preferred embodiments, the feed is substantially free of isomers of xylene, ethylbenzene and / or benzene. A feed that is substantially free of xylene isomers preferably includes less than about 3% by weight of xylene isomers, and more preferably less than about 1% by weight of xylene isomers, based on the total weight of the feed. A feed that is substantially free of ethylbenzene preferably includes less than about 5% by weight of ethylbenzene, and more preferably less than about 3% by weight of ethylbenzene, based on the total weight of the feed. A feed that is substantially free of ethylbenzene preferably includes less than about 5% by weight of ethylbenzene, and more preferably less than about 3% by weight of ethylbenzene, based on the total weight of the feed.

In certain embodiments, after the feed is catalytically converted to a product containing xylene isomers, at least a portion of the xylene isomers is isolated from the product. When isolation is carried out, the remaining product is depleted in xylene isomers relative to the product before separation and, therefore, as mentioned in this application, the product is depleted in xylene isomers. After separation, this product, depleted in xylene isomers, can be recycled to the feed. Accordingly, in these embodiments, the method can be described as a method in which a feed is catalytically converted to a product containing xylene isomers, xylene isomers are separated from the product, and the product is then recycled to the feed. In these embodiments, the recycled product preferably contains small (or only traces) amounts of xylene isomers and contains predominantly unreacted feeds, benzene, toluene and C ₉₊ aromatic hydrocarbons.

In a further embodiment of the method of the invention, the product contains xylene and ethylbenzene isomers present in a weight ratio of at least about 6 to 1, preferably at least about 10 to 1, and more preferably at least about 25 to 1 Formulating in other words, a method for converting a C ₉ aromatic hydrocarbon feed into a product containing xylene isomers involves contacting the feed on an appropriate catalyst under conditions suitable for the preparation of a weight ratio of xylene isomers to ethylbenzene in the product stream of at least about 6 to 1, preferably at least about 10 to 1, and more preferably at least about 25 to 1. Such a high weight ratio of xylene isomers to ethylbenzene in the product stream, it is advantageous in the further processing of hydrocarbons, when the product must be fractionated into its main components, that is, into aromatic hydrocarbons containing 6, 7, 8, and 9 carbon atoms. As a rule, further processing of the C ₈ aromatic hydrocarbon fraction must necessarily include the energy-consuming processing of ethylbenzene to convert it to benzene (processes for the elimination of ethyl groups). These deethylation processes can cause a decrease in the yield of xylene isomers. However, taking into account this significant absence of ethylbenzene in the liquid reaction product, and accordingly the significant absence of ethylbenzene in the C ₈ aromatic hydrocarbon fraction, a much less energy-consuming refining process can be used to free the ethylbenzene fraction. Additionally, the significant absence of ethylbenzene means that further hydrocarbon processing processes used to convert xylene isomers to para-xylene should not lead to a decrease in xylene yield, because deethylation processes are not necessary.

In addition, a significant absence of ethylbenzene is particularly desirable. As previously noted, although ethylbenzene can be used as a raw material for the production of styrene, such ethylbenzene must have a high degree of purification. Certain ethylbenzene, which is obtained by the disproportionation and transalkylation of benzene, toluene and C ₉ aromatic hydrocarbons, is necessarily present in a mixture containing other aromatic hydrocarbons. The separation of ethylbenzene from such a mixture is very difficult and very expensive. Therefore, from a practical point of view, this ethylbenzene cannot be used in the production of styrene. In practice, ethylbenzene is either used as an additive to gasoline (as an additive increasing the octane number in it) or is likely to undergo further disproportionation, leading to light gas (for example ethane) and benzene. According to the invention, however, the significant absence of ethylbenzene in the liquid reaction product and the C ₈ aromatic hydrocarbon fraction eliminates such processes.

In another embodiment of the method of the invention, the product contains xylene to methylethylbenzene (MEB) isomers in a weight ratio of at least about 1 to 1, preferably from at least about 5 to 1, and more preferably from at least about 10 to 1. As stated in other words, a method of converting a C ₉ aromatic hydrocarbon feedstock to a product containing xylene isomers involves contacting the feedstock with an appropriate catalyst under conditions suitable for producing weight the new ratio of xylene to methyl ethyl benzene isomers in the product is from at least about 1 to 1, preferably from at least about 5 to 1, and more preferably from at least about 10 to 1. The absence (or low amount) of methyl ethyl benzene in the product It is advantageous in that there are lower amounts of such unreacted or produced C ₉ aromatic hydrocarbons that need to be recycled back to the feed for conversion, thereby saving energy and reducing capital costs. atrats.

In yet another embodiment of the method of the invention, the product comprises C ₁₀ xylene to aromatic hydrocarbons in a weight ratio of at least about 3 to 1, preferably at least about 5 to 1, and more preferably at least about 10 to 1. formulating in other words, a method for converting a C ₉ aromatic hydrocarbon feed into a product containing xylene isomers involves contacting the feed on an appropriate catalyst under conditions suitable for the preparation of the weight ratio of xylene isomers to aromatic hydrocarbons C ₁₀ in the product is from at least about 3 to 1, preferably from at least about 5 to 1, and more preferably from at least about 10 to 1. Such high ratios are this is evidence that the dominant reaction, including C ₉ aromatic hydrocarbons, is a disproportionation reaction leading to xylene isomers and is not a reaction leading to C ₁₀ aromatic hydrocarbons, toluene and benzene. The absence or low amount of C ₁₀ aromatic hydrocarbons in the product is advantageous in that there are lower amounts of such unreacted or obtained C ₁₀ aromatic hydrocarbons that need to be recycled back to the feed for conversion, thereby saving energy and reducing capital costs. In cases where C ₁₀ aromatic hydrocarbons are present in the product, such C ₁₀ aromatic hydrocarbons are predominantly tetramethylbenzene, which can be recycled and more amenable to conversion to xylene isomers. Advantageously, C ₁₀ aromatic hydrocarbons do not include a large amount of ethyldimethylbenzene and / or diethylbenzene, both of which are more difficult to convert to xylene isomers and therefore less likely to recycle.

In a further embodiment of the method according to the invention, the product contains trimethylbenzene to methylethylbenzene in a weight ratio of at least about 1.5 to 1, preferably from at least about 5 to 1, more preferably from at least about 10 to 1, and even more preferably at least about 15 to 1. Stated in other words, the method comprising converting aromatic hydrocarbons including C ₉ feed to a product containing xylene isomers includes contacting the feed n a suitable catalyst under conditions suitable for obtaining a weight ratio of trimethylbenzene to methylethylbenzene in the product from at least about 1.5 to 1, preferably from at least about 5 to 1, more preferably from at least about 10 to 1, and even more preferably from at least about 15 to 1. To obtain the xylene isomer from trimethylbenzene, a single methyl group must be removed from the trimethylbenzene molecule. On the contrary, in order to obtain the xylene isomer from methylethylbenzene, it is necessary to replace the methyl group on the benzene core with a methyl group. Such a replacement is difficult to accomplish. Therefore, the high ratios of trimethylbenzene to methylethylbenzene are advantageous in that trimethylbenzene is more amenable to conversion to xylene isomers than methylethylbenzene and, therefore, is more recyclable.

In another additional embodiment of the method according to the invention, the product contains benzene to ethylbenzene in a weight ratio of at least from about 2 to 1, preferably from at least about 5 to 1, and more preferably from at least about 10 to 1 . Stated in other words, the method comprising converting C ₉ aromatic hydrocarbons feedstock to a product containing xylene isomers includes contacting the feed on the catalyst under conditions suitable to obtain a weight ratio benz l to ethylbenzene in the product from at least about 2 to 1, preferably from at least about 5 to 1, and more preferably from at least about 10 to 1. Such high ratios benefit from the fact that ethylbenzene such as obtained during disproportionation and transalkylation reactions, including aromatic hydrocarbons C ₉ has a lower value than a chemical feedstock, which leads to difficulties in the separation of ethylbenzene from a mixture of other aromatic hydrocarbons _8. As noted above, the C ₉ aromatic hydrocarbon and benzene molecule can be transalkylated to the xylene and toluene molecule. Thus, a high ratio of benzene to ethylbenzene in the product may be useful, considering that portions of the product enriched in xylene can be recycled to increase the yield of xylene isomers.

In another embodiment of the method according to the invention, the feed contains C ₉ aromatic hydrocarbons present in an amount (weight ratio) relative to the amount present in the product, from at least about 1.5 to 1, preferably from at least about 2 to 1, and more preferably at least about 4 to 1. Stated in other words, a process for converting hydrocarbons comprising C ₉ aromatic feed to a product containing xylene isomers includes contacting the feed to the catalyst under conditions suitable to obtain the weight ratio of aromatic hydrocarbons C ₉ present in the feed to obtain a weight ratio of aromatic hydrocarbons C ₉ present in the product of at least about 1.5 to 1, preferably at least about 2 to 1, and more preferably from at least about 4 to 1. This high conversion is advantageous in that there are lower amounts of unreacted C ₈ aromatic hydrocarbons that need to be recycled to a backlog to feedstock for conversion, thus saving energy and lowering capital expenditures.

In yet another embodiment of the method of the invention, the feed contains methylethylbenzene present in an amount (weight ratio) relative to the amount present in the product from at least about 2 to 1, preferably from at least about 5 to 1, and more preferably from at least about 10 to 1. Stated in other words, a process for converting hydrocarbons comprising C ₉ aromatic feed to a product soderzhaschey xylene isomers includes contacting the feed on the catalyst under conditions x, suitable for obtaining a weight ratio of methylbenzene present in the feed to a weight ratio of methylbenzene present in the product from at least about 2 to 1, preferably from at least about 5 to 1, and more preferably from at least from about 10 to 1. Such a high ratio is evidence that the method according to the invention can efficiently convert raw materials in which there is a high ratio of methylbenzene present among aromatic carbohydrates Hordes C ₉ . Indeed, high ratios show that the reactions are effective for converting approximately 50%, preferably 90%, and most preferably 95% methylbenzene, into light gas and lighter aromatic hydrocarbons. In addition, such high ratios are evidence that reactions do not produce methylethylbenzene.

The disclosed methods are mainly illustrated in the only accompanying drawing, in which the embodiment, generally designated as 10, includes a reactor 12 and a liquid product separator 14, which is usually a distillation or distillation column / tower type column. More specifically, the feed in the feed pipe 16 and the hydrogen-containing gas in the gas pipe 18 are combined and heated in the furnace 20. The heated mixture passes to the reactor 12, where the feed is catalytically reacted in the presence of hydrogen to produce a product. The product exits the reactor 12 through the product line 22 and is then cooled in the heat exchanger 24. The cooled product exits the heat exchanger 24 through the transport pipe 26 and passes into the container 28, in which gas and liquids are separated from each other. As necessary (for example, when the transalkylated feed contains C ₉ aromatics), fresh hydrogen can also directly enter reactor 12 through gas line 18A. Gases, primarily hydrogen, are removed from vessel 28 and the portions are compressed (compressor not shown) and recycled through gas line 30 to hydrogen-containing gas in gas line 18, while residues can be discharged through discharge line 32. Liquids are removed from vessel 28 through the transport pipe 34 and sent to the liquid separator 14. Inside the separator 14, the components comprising the product are separated.

When embodiment 10 is used to transalkylate a feed (feed line 16) containing predominantly C ₉ aromatic hydrocarbons (and also containing some benzene and toluene), the main components including the product in separator 14 will be xylene isomers and toluene. Xylene isomers exit separator 14 through product line 36. One or more recirculation pipelines 38 and 40 can transport unreacted C ₉ aromatics and a product enriched in xylene isomers (usually containing toluene), respectively, back to reactor 12, for example, combining these products with fresh feed in the feed line 16. Pipelines 36A, 38A, and 40A may remain unused when the transalkylated feed contains predominantly C ₉ aromatic hydrocarbons; however, these pipelines can be used to recycle or discharge certain components in the product as needed.

When embodiment 10 is used to disproportionate a feed (in a feed line 16) containing predominantly toluene, the main components including the product in the separator 14 will be xylene isomers, toluene and benzene. Xylene isomers exit separator 14 through product line 38A. The recirculation pipe 36A can be used to transport the toluene back to the reactor 12, for example, combining this toluene with fresh feed in the supply pipe 16. Benzene can be removed from the process through the pipe 40A. Pipelines 36, 38, and 40 may remain unused when the disproportioned feed contains predominantly toluene; however, these pipelines can be used to recycle or discharge certain constituents in the product as needed.

Thus, in embodiment 10, the inlet is feed (16) and a hydrogen-containing gas (18), and the process outlet is the product of xylene isomers (36 or 38A). Since transalkylation and disproportionation performed in the process require the presence of a certain amount of methyl groups present relative to the number of benzene groups, some removal of the resulting benzene and toluene from the whole process can be carried out.

Included in the disclosed method according to the invention (and its various embodiments) is the understanding by qualified specialists in the technology of the corresponding process equipment and controls necessary for implementing this method. Such process equipment includes, but is not limited to, an appropriate piping system, pumps, valves, standard process equipment (e.g., reaction vessels with corresponding inlets and outlets, heat exchangers, separation plants, etc.), associated process instrumentation and quality control equipment, if any. Any other processing equipment, especially which is particularly preferred, is defined in this application.

In general, the disclosed method is carried out in a reactor containing an un-sudified catalyst suitable for converting a feed into a product containing xylene isomers. Suitable catalysts mainly include a carrier impregnated with a hydrogenation component and a carrier containing a binder and a sieve, each of which are described in more detail below. Typically, the sieve contains active sites for the conversion of raw materials into xylene isomers. The catalyst must be such that raw materials, recycling, and product can access these active sites and cross the pores of the catalyst. The suitability of the catalyst will depend on a number of reasons. One such reason is the size of the molecules contained in the feed, recycle and product, which may affect the interaction with the catalyst. Although active sites can be found on the external surfaces of the catalyst particles, most catalytically active sites will be present inside the pores of the catalyst particles and, more specifically, within the pores of the sieve. Thus, molecules small enough to diffuse (or cross) through the pores and reach the active sites can be catalytically converted there into a product. If the product is small enough, then the product can also cross the pores and exit the reactor in a timely manner. Molecules that are too large to cross the pores, however, will bypass the catalyst and pass unreacted through the reactor, because they will not fit into the pores where most of the catalytic centers are located. While active centers will be located on the external surfaces of the catalyst (and not only inside the pores), a porous material that does not allow diffusion of these large molecules is ideally suited for the desired conversion. Similarly, the product molecules that form within the pores can be so large that their transport from the pores can be very slow, and they can transform into smaller (yet undesirable) molecules that dissipate more quickly through the catalyst. Thus, the catalyst should contain pores of sufficient size to accommodate not only the molecules within the feed, but also those molecules that can be expected as a result of the conversion.

As noted above, the disclosed methods contemplate feedstocks, recycling, and products containing various kinds of molecules. The size of the molecules present in each of these will minimally determine the pore size of a sieve suitable for the catalyst. With _9+, aromatic hydrocarbons are, of course, larger in size than the isomers of xylene, toluene and benzene. A sieve containing large pores (i.e., from at least about six angstroms to about eight angstroms) will allow the passage of C ₉₊ aromatic hydrocarbons. In contrast, a sieve containing small pores (i.e., between approximately three angstroms and less than approximately four angstroms) will generally not allow any of these molecules to pass. Sieve with an average pore size will allow some of these molecules to pass, but not others. For example, C ₉₊ aromatic hydrocarbons will not pass at all through a sieve containing pores with an average size (i.e., between approximately four angstroms and less than approximately six angstroms), while xylene isomers, toluene, benzene and smaller molecules will go through these sieves.

Sieves (also referred to as “molecular sieves” in this application) suitable for use in the disclosed method of the invention include a wide variety of natural and synthetic, crystalline, porous oxides having channels, cells and cavities of molecular size. These sieves are typically formed from silica, alumina and / or phosphorus oxide. Sieves preferred for use in accordance with the disclosed methods are selected from the group consisting of aluminosilicates (also known as zeolites), aluminophosphates, silicoaluminophosphates and mixtures thereof. Such sieves can have large pores or pores with an average size depending on the reactants, intermediates and products, probably for their interaction in the disclosed methods. For example, large pore sieves should be used when a feed, intermediate or product may suggest the presence of C ₉₊ aromatic hydrocarbons. Sieve with a large pore size can also be used when raw materials, intermediate products or the final product may suggest the presence of molecules smaller in size than C ₉₊ aromatic hydrocarbons; however, a sieve with an average pore size in such cases may also be or better suited than a sieve with a large pore size. Suitable sieves with a large pore size have a pore size of at least about six angstroms. Suitable sieves with an average pore size have a pore size of approximately four angstroms and less than approximately six angstroms. In general, the support comprises from about 20% by weight to about 85% by weight of the sieves, based on the total weight of the catalyst. As described in more detail below, however, the amount of sieve will be related to the amount of binder present in the carrier.

Examples of coarse sieves include, but are not limited to, beta (BEA), EMT, FAU (e.g. zeolite X, zeolite Y (USY)), MAZ, mascite, mordenite (MOR), zeolite L, LTL (IUPAC Zeolite Nomenclature) . Preferred large-pore zeolites include zeolites beta (BEA), Y (USY) and mordenite (MOR), general descriptions of each of which can be found in Kirk Othmer's "Encyclopedia of Chemical Technology," 4 ^th Ed., Vol.16, pp. 888 -925 (John Wiley & Sons, New York, 1995) (hereinafter "Kirk Othmer's Encyclopedia"), and in WM Meier et al., "Atlas of Zeolite Structure Types," A1-A5 and 1-16 (4 ^th Ed. , Elsevier, 1996) (hereinafter "Meier's Atlas"), the disclosures of which are incorporated herein by reference. Mixtures of these zeolites are also suitable. These zeolites can be obtained from commercial sources, such as, for example, Engelhard Corporation (Iselin, New Jersey), PQ Corporation (Valley Forge, Pennsylvania), Tosoh USA, Inc. (Grove City, Ohio) and UOP Inc. (Des Plaines, Illinois). More preferably, a large pore zeolite for use in the invention is a mordenite type zeolite. Examples of large pore aluminophosphates include, but are not limited to, SAPO-37 and VFI. Mixtures of these aluminophosphates are also suitable.

Examples of medium pore zeolites include, but are not limited to, University of Edinburgh One (EUO), ferrierite (FER), Mobile eleven (MEL), Mobile fifty seven (MFS), Mobile five (MFI), Mobile twenty three (MTT), the new eighty-seven (NES), THETA-ONE (TON) and mixtures thereof. Preferably, however, medium pore zeolites include Mobile Five (MFI) and Mobile Eleven (MEL). Preferred Mobil Five zeolites (MFIs) include those selected from the group consisting of ZSM-5, silicalite, related isotypic structures, and mixtures thereof. Preferred Mobil-eleven zeolites (MEL) include those selected from the group consisting of ZSM-11, related isotypic structures, and mixtures thereof. General descriptions of medium pore zeolites can be found in Kirk Othmer's Encyclopedia and Meier's Atlas, the disclosures of which are incorporated herein by reference. These types of zeolites can be obtained from commercial sources, such as, for example, ExxonMobil Chemical Company (Baytown, Texas), Zeolyst International (Valley Forge, Pennsylvania) and UOP Inc. (Des Plaines, lllnois). An example of a suitable medium pore aluminophosphate is aluminophosphate-elevent (AEL).

As noted above, the carrier includes a sieve and a macroporous binder. “Micro”, “meso” and “macro” - prefixes to the terms “pore”, “pore volume,” and “porous” are known to those skilled in the art of preparing and using catalysts. In this prior art, micropore mainly refers to a pore volume with a radius of about twenty angstroms (two nanometers (nm)) or less). Mesopore mainly refers to the volume of pores having radii larger than about twenty angstroms (two nm) and less than about 500 angstroms (50 nm) in size. Macropore mainly refers to the volume of pores having radii having sizes greater than about 500 angstroms (50 nm). See, for example, S.M. Auerbach, "Handbook of Zeolite Science and Technology," 291 (Marcel Dekker, Inc., New York, 2003).

Suitable macroporous binders include, but are not limited to, aluminum oxides, aluminum phosphates, clays, silicas, aluminas, silicas, silicates, titanium dioxide, zirconia, and mixtures thereof. Some of these binders can also provide advantages in terms of easily achieving suitable physical properties by steam treatment to increase the average pore diameter, without noticeably reducing the volume of the pore space, as described in more detail below. Preferred alumina include γ-alumina, η-alumina, pseudobohemite and mixtures thereof. Typically, the carrier may include up to about 50% of the weight of the binder, based on the total weight of the carrier, and preferably includes from about 10% to about 30% of the weight of the binder, based on the total weight of the carrier. The weight ratio of the sieve to the binder is preferably from about 20: 1 to about 1:10, and more preferably from about 10: 1 to about 1: 2.

The catalyst is preferably bifunctional because it includes active sites not only as an acid component in the sieve, but also active sites as a hydrogenation component. Accordingly, the catalyst also includes a hydrogenation component. The hydrogenation component included in the catalyst facilitates the conversion of the feed to a product containing xylene isomers. More specifically, the hydrogenation component catalyzes the reaction between molecular hydrogen and free olefins that may be present in the reactor, which prevents the olefins from deactivating the catalytic (acid) sites in the sieve. Molecular hydrogen is believed to saturate the olefins so that the olefins cannot react with aromatic hydrocarbons at the catalytic (acid) centers to form unwanted heavy by-products.

Preferably, the hydrogenation component is a metal or a metal oxide. The metal is preferably selected from the group consisting of metals of group VIB, metals of group VIIB, metals of group VIII, and combinations thereof. Among this group, Group VIB metals are preferred. Preferably, Group VIB metals include, but are not limited to, chromium, molybdenum, tungsten, and combinations thereof. The Group VIB metal oxide is preferably selected from the group consisting of molybdenum oxide, chromium oxide, tungsten oxide and combinations of any two or more, where the valency corresponding to the oxidation state of the metal can be any possible valency corresponding to the oxidation state. For example, in the case of molybdenum oxide, the valency corresponding to the oxidation state of molybdenum may be 0, 2, 3, 4, 5, 6, or a combination of any two or more.

Examples of suitable Group VIB metal compounds include, but are not limited to, chromium, molybdenum, and / or tungsten-containing compounds. Suitable chromium compounds include, but are not limited to, chromium (II) acetate, chromium (II) chloride, chromium (II) fluoride, chromium (III) 2,4-pentanedionate, chromium (III) acetate, chromium (III) acetylacetonate, chloride chromium (III), chromium (III) fluoride, chromium hexacarbonyl, chromium (III) nitrate and chromium (III) perchlorate. Suitable tungsten-containing compounds include, but are not limited to, tungsten acid, tungsten (V) bromide, tungsten (IV) chloride, tungsten (VI) chloride, tungsten hexacarbonyl and tungsten (VI) oxychloride. Molybdenum-containing compounds are preferred metals, and such compounds include, but are not limited to, ammonium dimolybdate, ammonium heptamolybdate (ammonium), ammonium molybdate, ammonium phosphomolybdate, dioxomolybdenum (VI) bis (acetylacetonate), molybdenum, molybdenum, molybdenum, molybdibenum (II), molybdenum (II) chloride, molybdenum (III) bromide, molybdenum (III) chloride, molybdenum (IV) chloride, molybdenum (V) chloride, molybdenum (VI) fluoride, molybdenum (VI) oxychloride, molybdenum tetrachloride ( Vi) potassium molybdate and oxide molybdenum, in which the valency corresponding to the oxidation state of molybdenum can be 2, 3, 4, 5, and 6, and combinations of two or more. Preferably, the Group VIB metal compound is ammonium molybdate due to its prevalence and relative simplicity with which molybdenum can be included in preferred sieves.

Examples of suitable Group VIIB metal compounds include, but are not limited to, rhenium containing metal compounds, such as, for example, (NH ₄ ) ReO ₄ , Re ₂ O ₇ , ReO ₂ , ReCl ₃ , ReCl ₅ , Re (CO) ₅ Cl, Re (CO) ₅ Br, Re ₂ (CO) _10, and combinations thereof. Examples of suitable Group VIII metal compounds include, but are not limited to, nickel, palladium, and platinum compounds. Examples of nickel-containing metal compounds include, but are not limited to, nickel chloride, nickel bromide, nickel nitrate, and nickel hydroxide. Examples of palladium-containing metal compounds include, but are not limited to, palladium chloride, palladium nitrate, palladium acetate and palladium hydroxide. Examples of platinum-containing metal compounds include, but are not limited to, platinum chloride acid (H ₂ PtCl ₆ · xH ₂ O), hexachloroplatinic (IV) acid, platinum (II) or (IV) chloride (chloroplatinate), platinum bromide (I) or (IV ), platinum (II) iodide, platinum (II) cis or transdiamine chloride, platinum (IV) cis or transdiamine chloride, platinum (II) diamine nitrate, platinum (II) chloride (ethylene diamine), platinum tetramine chloride or II) (Pt (NH ₃ ) ₄ Cl ₂ · H ₂ O or Pt (NH ₃ ) ₄ Cl ₂ ), platinum (II) tetramine nitrate, platinum (II) chloride (ethylene diamine), platinum (II) tetramine nitrate (Pt (NH ₃ ) ₄ (NO ₃ ) ₂ ), tetrakis (triphenylphosphine) platinum (0), cis- or trans-bis (triethylphosphine) platinum (II) chloride, cis- or trans-bis (triethylphosphine) platinum (II) oxalate, cis chloride bis (triphenylphosphine) platinum (II), bis (triphenylphosphine) platinum (IV) oxide, (2,2'-6 ', 2 ”-terpyridine) platinum (II) chloride dihydrate, bis (acetonitrile) platinum dichloride, cis dichloride bis (benzonitrile) platinum, platinum (II) acetylacetonate, platinum (II) chloride or bromide (1c, 5c-cyclooctadiene), platinum nitrosyl nitrate and platinum tetrachlorodiamine (IV). Other Group VIII metal compounds that may be used include cobalt, rhodium, iridium, and ruthenium compounds.

The amount of a hydrogenation component (e.g., metal or metal oxide) present in the catalyst must be sufficient to be effective for transalkylation, dealkylation and disproportionation processes. Accordingly, the amount of the hydrogenation component is preferably in the range of from about 0.1% to about 20% by weight, more preferably from about 0.5% to about 10% by weight, and even more preferably from about 1% to 5% by weight, based on total weight of the catalyst. Molybdenum is a preferred metal, and, preferably, the carrier is impregnated with ammonium heptamolybdate. Accordingly, the catalyst preferably comprises from about 0.5% by weight to about 10% by weight of molybdenum or molybdenum oxide, more preferably from about 1% by weight to about 5% by weight of molybdenum or molybdenum oxide, and even more preferably about 2% by weight of molybdenum or molybdenum oxide, calculated on the total weight of the catalyst. If a combination of metals or metal oxides is used, the molar ratio of the second, third and fourth metal oxides to the first metal oxide should be in the range of from about 1: 100 to about 100: 1.

Any methods suitable for incorporating metals or metal oxides into the catalyst support, such as, for example, impregnation or adsorption, can be used to prepare the catalyst. For example, a carrier can be prepared by mixing a sieve and a binder by mixing, dry mixing, plasticizing or extrusion. Preferably, mixing occurs at atmospheric pressure, but can be carried out at pressures slightly above and below atmospheric pressure. The resulting mixture can then be dried in air at a temperature in the range of from about 20 ° C to about 200 ° C, preferably from about 25 ° C to about 175 ° C, and more preferably from 25 ° C to 150 ° C for from about 0.5 hours to about 50 hours, preferably from about one hour to about 30 hours, and more preferably from one hour to 20 hours. After the sieve and binder are sufficiently mixed and dried (to form an extrudate, for example), the support may optionally be calcined in air at a temperature in the range of from about 200 ° C to 1000 ° C, preferably from about 250 ° C to about 750 ° C, and more preferably from about 350 ° C to about 650 ° C. Calcination can be carried out within about 1 hour to about 30 hours, and more preferably from about 2 hours to about 15 hours, resulting in a calcined carrier.

The metal or metal oxide may be included in the prepared carrier or, it may be included in the sieve / binder mixture used to form the carrier. Since the binder is combined with a metal compound, it can subsequently be converted to a metal oxide by heating at an elevated temperature, mainly in air. As noted above, the metal or metal oxide is preferably selected from the group of VIB metals such as chromium, molybdenum, tungsten, and combinations and their oxides. The metal compound may be dissolved in a solvent before being contacted with the carrier. Preferably, however, the metal compound is an aqueous solution. Contacting can be performed at any temperature and pressure. Preferably, however, the contacting is carried out at a temperature in the range of from about 15 ° C to about 100 ° C, more preferably from about 20 ° C to about 100 ° C, and even more preferably from about 20 ° C to about 60 ° C. Contacting preferably also occurs at atmospheric pressure, for a period of time sufficient to ensure that the metal oxide is included in the carrier. In general, this length of time is from about 1 minute to about 15 hours, and preferably from about 1 minute to about 5 hours.

As described in more detail below, the catalyst (and support) can be prepared by incorporating macropores, for example, using a pore former, in preparing the catalyst (and support) using a binder that contains such macropores (i.e., a macroporous binder), or by exposing the catalyst to heat (in the presence or absence of steam). A pore former is a material that promotes the formation of pores in the catalyst carrier in such a way that the carrier contains more and / or larger pores than if the pore former was not used in the preparation of the carrier. The methods and materials necessary to ensure a suitable pore size are well known to those skilled in the art of catalyst preparation. Examples of blowing agents are disclosed by Doyle et al. In the application of 2004/00220047 A1, the disclosure of which is incorporated herein by reference. Examples of suitable blowing agents include, but are not limited to, acids, anionic surfactants, cationic surfactants, polysaccharides, waxes, and mixtures thereof. Suitable acids include citric acid, lactic acid, oxalic acid, stearic acid, tartaric acid, and mixtures thereof. Suitable anionic surfactants include sodium alkylbenzenesulfonates, alkyl ethoxysulfates, alkyl sulfates, ammonium carbonate ((NH ₄ ) ₂ CO ₃ ), silicon carboxylates, silicon phosphate esters, silicon sulfates, and mixtures thereof. Suitable cationic surfactants include silicon amides, quaternary silica amides, quaternary amines silicon imidazoline, tall oil trimethylammonium chloride, and mixtures thereof. Suitable polysaccharides for use as blowing agents include carboxymethyl cellulose, cellulose, cellulose acetate, methyl cellulose, polyethylene glycol, starch, walnut powder, and mixtures thereof. Waxes suitable for use as blowing agents include microcrystalline wax, brown coal wax, paraffin wax, polyethylene based wax, and mixtures thereof. Preferably, the blowing agent is mixed with a binder to provide a more uniform distribution of the blowing agent in the binder and, therefore, to ensure that a macroporous binder is obtained.

The catalyst may be heated to obtain pores having an average radius of greater than about 500 angstroms (50 nm). This heating step can be performed in the absence of steam or in the presence of steam, which is also known as steam treatment, steam impregnation or steam treatment. Steam treatment can be carried out as an alternative to using a blowing agent, or as an additional step when the blowing agent has already been used. In general, steam treating the catalyst may optionally increase the average pore diameter without leading to a noticeable reduction in pore volume so as to lead to a catalyst suitable for use in accordance with the disclosed methods of the invention. Such steam treatments are well known to those skilled in the art of catalyst development and are mainly disclosed, for example, in US 4,395,328, the disclosure of which is incorporated herein by reference. Preferably, the catalyst is heated in the presence of steam at a sufficiently elevated temperature, steam pressure and time interval to increase the average pore diameter of the formed catalyst in the absence of any noticeable decrease in pore volume. Preferably, steam is used at a pressure of from about 30 kPa (4.4 psig) to about 274 kPa (25 psig). The time during which the catalyst is in contact with steam is from about fifteen minutes to about three hours, and preferably from about 30 minutes to about two hours. The elevated temperature at which the steaming is carried out is from about 704 ° C (1,300 ° F) to about 927 ° C (1,700 ° F), preferably from about 760 ° C (1,400 ° F) to about 871 ° C (1,600 ° F). While specific combinations of values for these steam conditions are not provided, any combination that provides an increase in the average pore diameter without any noticeable change in pore volume is suitable. Steam treatment can also be used to improve the selectivity, abrasion resistance and thermal stability of the catalyst.

The distribution of the pore space volume and the macropore volume of the catalysts can be determined by methods known to those skilled in the art of catalyst preparation. Mercury intrusion porosimetry (e.g., ASTM D4284-03), which is a well-known technique for measuring the pore size distribution of porous materials, is one suitable technique. According to this technique, small samples (for example, from about 0.25 grams to about 0.5 grams) are first degassed and then placed in a mercury bath. Mercury is a non-wetting fluid for most porous materials of interest, such that increasing pressure is necessary to push mercury into smaller and smaller pores. A porosimeter (for example, a Quantachrome Poremaster 60 porosimeter manufactured by Quantachrome Instruments of Boynton Beach, Florida) measures the volume of mercury that enters the sample as pressure increases. This volume of mercury is then associated with the pore diameter, which is determined by assuming an annular, cylindrical configuration of the pore. As the pressure is increased, a wide range of pore sizes can be studied. Porosity measurements can be calculated using the Washburn equation:

PD = -4γcos (θ),

where P is the applied pressure, D is the diameter, γ is the surface tension of the mercury (480 dyne per centimeter), and θ is the contact angle between the mercury and the pore wall (average value 140 °). Preferably, the macropore volume of the catalyst is from about 0.02 cubic centimeters per gram (cm ³ / g) to about 0.5 cm ³ / g, more preferably from about 0.05 cm ³ / g to about 0.35 cm ³ / g, and even more preferably from about 0.1 cm ³ / g to about 0.3 cm ³ / g.

While both fixed-bed processes and expanded-bed processes are discussed herein, fixed-bed processes are preferred. In fixed-bed processes, feedstock and hydrogen-containing gas pass from top to bottom through the catalyst nozzle under conditions of temperature, pressure, hydrogen flow rate, space velocity, etc., which vary to some extent depending on the choice of feedstock, reactor capacity, and other factors, known to those skilled in the art. Where reactions may involve heat consumption or heat generation, fixed bed reactors may include multiple tubes, each filled with catalyst through which reactants and products will pass. From the annulus, a heat transfer medium may be used to provide or dissipate heat. Toluene disproportionation reactions are mainly isothermal, while transalkylation reactions are generally slightly exothermic. Thus, fixed-bed reactors using such tubes and coolants may be useful for better control and / or optimization of reaction temperatures.

The fracture strength (or service life) of the catalyst is important in fixed bed operations due to the pressure drop resulting from the passage of the feed and hydrogen-containing gas through the filled catalyst bed. The size and shape of the catalyst can also be important in fixed bed operations because of their effect not only on the pressure drop across the bed, but also on the loading of the catalyst and the contact between the catalyst and the feed components. The use of large catalyst particles near the top of the catalyst layer and smaller particles throughout the remaining layer can advantageously lead to a reduced pressure drop. A catalyst in the form of spherical particles or an extrudate, preferably from about 0.01 inch (0.25 mm) to about 0.1 inch (2.5 mm) in diameter, should maintain adequate contact between the catalyst and the feed, avoiding increased overpressure through the catalyst bed. More preferably, the catalyst particles have an average particle size of from about 1/32 inch (0.8 mm) to about 1/12 inch in diameter (2.1 mm). Trilobar, trefoil, cruciform, and “C” shaped catalysts common in the art should be suitable in terms of maximizing catalyst efficiency and maintaining a high level of contact between the catalyst and feed components.

Other physical properties that are not critical to the activity of the catalyst, but which can affect performance, include bulk density, mechanical strength, abrasion resistance, and average particle size. The bulk density of the catalyst is preferably from about 0.3 g / cm ³ to about 0.5 g / cm ³ . The mechanical strength should be at least very sufficient for use in this process without undesired fragmentation or other damage. In the same way, the abrasion resistance should be quite sufficient so that the catalyst particles retain the particle upon contact of the particle in the same way as upon contact between the particles and the interior of the reaction zone, especially in processes on an expanded layer. Preferably, the fracture toughness of the catalyst composition is such that a 1/8-inch (3.2 mm) particle in length and 1/32-inch (0.8 mm) in diameter can withstand at least about three pounds of pressure. The particle size may vary slightly depending on the particular process that is used. The shape of the particles, however, can vary significantly, as noted above, depending on the requirements of the method.

Depending on the intensity of the operation and other process parameters, the catalyst will age. Like catalyst lifetimes, its activity for the desired reactions tends to decrease slowly due to the formation of coke or poisons from the feed on the surfaces of the catalyst. The catalyst may be maintained at an initial level of activity or periodically regenerated to its initial level of activity by methods well known to those skilled in the art. Alternatively, the old catalyst may simply be replaced with a new catalyst.

Provided that the old catalyst is not replaced by a new catalyst, the old catalyst may often require regeneration once every two years, with a frequency of once a year, or, if possible, with a frequency of once every six months. As used in this application, the term “regeneration” means obtaining again at least part of the initial activity of the molecular sieve, burning any coke deposits on the catalyst with oxygen or an oxygen-containing gas. The literature is full of catalyst regeneration methods that can be used in the method of the present invention. Some of these regeneration methods include chemical methods to increase the activity of deactivated molecular sieves. Other regeneration methods relate to methods for regenerating coke deactivated catalysts by burning coke with an oxygen-containing gas stream, such as, for example, a cyclic stream of regeneration gases or continuous circulation of an inert gas containing an amount of oxygen in a closed loop of the system through the catalyst bed.

The catalyst for use in the disclosed method is particularly suitable for regeneration by oxidation or burning of catalyst deactivating carbonate deposits (also known as coke) with oxygen or an oxygen-containing gas. Although the methods by which the catalyst can be reduced by burning coke may be different, they are preferably carried out under conditions of temperature, pressure and space velocity of the gas, for example, which are the least thermally damaging to the regenerated catalyst. It is also preferable to carry out regeneration in a timely manner to reduce process downtime in the case of a fixed bed reactor system or equipment size, in the case of a continuous regeneration process. A spare reactor can be provided to limit the process downtime to the extreme in a multi-reactor configuration. For example, in a multi-reactor configuration using five reactors, at any given time, one of the reactors may be in regeneration and be autonomous relative to the process. This autonomous reactor can be commissioned while the other is autonomous with minimal disruption / interruption of the entire process.

Although optimal regeneration conditions and methods are well known to those skilled in the art, catalyst regeneration is preferably achieved under conditions including a temperature range from about 550 ° F (about 287 ° C) to about 1300 ° F (about 705 ° C) from approximately zero psig (psig) (approximately zero megapascals (MPa)) to approximately 300 psig (approximately two MPa), and the oxygen regeneration gas content will approximate flax from 0.1 mole percent to about 25 mole percent. The oxygen content in the regeneration gas can usually be increased during the catalyst regeneration procedure based on the temperatures at the outlet of the catalyst bed in order to regenerate the catalyst as quickly as possible, avoiding process conditions that contribute to catalyst poisoning. Preferred catalyst regeneration conditions include a temperature in the range of about 600 ° F (about 315 ° C) to about 1150 ° F (about 620 ° C), a pressure in the range of about zero psig (about zero MPa) to about 150 psig (about one MPa) and the oxygen content of the regeneration gas is from about 0.1 molar percent to about 10 molar percent. Oxygen-containing regeneration gas mainly includes nitrogen and carbon combustion products, such as carbon monoxide and carbon dioxide, to which oxygen has been added in the form of air. However, it is possible that oxygen can be introduced into the regeneration gas as pure oxygen, or as a mixture of oxygen diluted with another gaseous component. Preferably, the oxygen-containing gas is air.

Conditions suitable for carrying out the method of the invention may include an hourly average feed rate (WHSV) of a liquid feed stream in the range of from about 0.1 to about 30, preferably from about 0.5 to about 20, and most preferably from about 1 to about 10 weight units of raw material per unit catalyst mass per hour. Hydrogen-containing gas (e.g. molecular hydrogen) is present in a molar ratio relative to hydrocarbons in the feed from about 0.1: 1 to about 10: 1, preferably from about 0.5: 1 to about 8: 1, and more preferably from about 1: 1 to about 6: one.

In general, the pressure can range from about 0.17 MPa (about 25 psig) to about 6.9 MPa (about 1000 psig), preferably from about 0.34 MPa (about 50 psig) to about 4.1 MPa (about 600 psig), and more preferably from about 0.69 MPa (approximately 100 psig) to approximately 2.76 MPa (approximately 400 psig). The temperature suitable for carrying out the method according to the invention is in the range from about 200 ° C (about 392 ° F) to about 800 ° C (about 1472 ° F), more preferably from about 300 ° C (about 572 ° F) to about 600 ° C (approximately 1112 ° F) and even more preferably from approximately 350 ° C (approximately 662 ° F) to approximately 500 ° C (approximately 932 ° F).

Sufficient porosity is believed to be important in terms of achieving a high exposure of the reagents to the catalytically active sites, while a significant amount of macropore is believed to be necessary to guarantee access to the sites and to remain active. However, if the pore volume is too high, mechanical strength and bulk density of the catalyst may suffer. Thus, an appropriate balance must be achieved to ensure that the catalyst best suits its intended purpose.

EXAMPLES

The following examples are presented to facilitate a better understanding of the disclosed methods. They are presented for illustration only and are not intended to limit the scope of protection of the claimed methods. In all examples, the micropore volume and pore size distribution (when determined) were determined by nitrogen desorption, and the macropore volume was determined by the penetration of mercury using a mercury porosimeter. Example 1 illustrates the conversion of a nitration grade toluene to a product containing benzene and xylene isomers on a catalyst carrier lacking macropores. For comparison, Examples 2-8 explain the conversion of such a feed to a product containing benzene and xylene isomers on a catalyst carrier containing macropores. The comparison shows that the catalyst carrier containing macropores leads to improved conversion, determined by a higher toluene conversion and higher selectivity for xylene isomers. Example 9 illustrates the conversion of nitration grade toluene on a catalyst with a lack of macropore volume and preserving the macropore volume and stability of each catalyst.

Examples 10 and 11 illustrate the ability of macroporous catalysts impregnated with molybdenum oxide to convert raw materials containing toluene, benzene and some light non-aromatic hydrocarbons. Examples 12 and 13 illustrate the ability of macroporous catalysts impregnated with molybdenum oxide to convert raw materials containing C ₉₊ aromatic hydrocarbons. Examples 14 and 15 illustrate the ability of macroporous catalysts impregnated with molybdenum oxide to convert raw materials predominantly containing C ₉ aromatic hydrocarbons. Example 16 illustrates the ability of a macroporous catalyst impregnated with molybdenum oxide to convert a feed containing toluene and C ₉ aromatics. Example 17 illustrates the ability of a macroporous catalyst impregnated with molybdenum oxide to convert a feed containing toluene and C ₉₊ aromatic hydrocarbons. Collectively, these examples demonstrate that various raw materials can be used in the disclosed methods and can recycle almost any by-product without significant process changes and without the need for catalyst replacement.

Catalyst Preparation

Many different catalysts were prepared and tested as described below. For comparative purposes, the catalysts “X” and “H” contained carriers having insignificant macropore volumes, while other catalysts contained carriers having significant macropore volumes.

Catalyst X was prepared with zeolite H-mordenite (commercially available from Engelhard Corporation (Iselin, New Jersey)) having a Si / Al ratio of 41.6 and a sodium (Na) level of 130 ppm. The carrier was prepared by mixing the zeolite with a binder of alumina to form a suspension. The suspension was then extruded to form 1/12-inch cylindrical tablets (80% sieve / 20% binder) and then calcined. An aqueous solution of ammonium heptamolybdate was then mixed with and impregnated on an extrudate to obtain a mordenite catalyst having 2% molybdenum uniformly distributed. The impregnated catalyst was then calcined at approximately 500 ° C for from about one hour to about three hours. A macropore volume of greater than about 50 nm for catalyst “X” was determined by mercury adsorption methods as 0.018 cm ³ / g.

Catalysts A through G were prepared with zeolite H-mordenite (commercially available from Engelhard Corporation) having a Si / Al ratio of 41.6 and a sodium (Na) level of 130 ppm. The carrier was prepared by mixing zeolite with a binder of alumina to obtain a suspension. A pore-forming reagent was added to the suspension, and the resulting mixture was then extruded to form either 1/12-inch cylindrical tablets or 1/16-inch three-part tablets (80% sieve / 20% binder). (Regarding Catalyst E, the resulting mixture was then extruded to form 1/12-inch cylindrical tablets (70% sieve / 30% binder)). Table 1 below indicates extruded tablets for each catalyst. The extrudate was then calcined, and the pore-forming reagent was split by heat treatment. An aqueous solution of ammonium heptamolybdate was then mixed with and impregnated on an extrudate to obtain a mordenite catalyst having 2% molybdenum uniformly distributed. The impregnated catalyst was then calcined at approximately 500 ° C for from about one hour to about three hours. A macropore volume of greater than about 50 nm for these catalysts was determined by mercury adsorption techniques and is indicated in Table 1 below for each catalyst.

Catalyst “H” was prepared with a laboratory-synthesized zeolite Na-mordenite (commercially available from Engelhard Corporation). The zeolite was subjected to ion exchange to provide an N-mordenite zeolite having a Si / Al ratio of 36.1 and a sodium (Na) level of 260 ppm. The carrier was prepared by mixing zeolite with a binder of alumina to obtain a suspension. A pore-forming reagent was added to the suspension, and the resulting mixture was then extruded to form 1/16-inch (1 inch ≈ 2.54 cm) triple tablets (80% sieve / 20% binder). An aqueous solution of ammonium heptamolybdate was then mixed with and impregnated on an extrudate to obtain a mordenite catalyst having 2% molybdenum uniformly distributed. A macropore volume of greater than about 50 nm for the “H” catalyst was determined by mercury adsorption methods as 0.01 cm ³ / g.

The catalyst “I” was prepared with laboratory-synthesized zeolite Na-mordenite (commercially available from Engelhard Corporation). The zeolite was subjected to ion exchange to supply the zeolite N-mordenite having a Si / Al ratio of 36.1 and a sodium (Na) level of 260 ppm. The carrier was prepared by mixing zeolite with a binder of alumina to obtain a suspension. The suspension was then extruded to form 1/16-inch tri-lobe tablets (80% sieve / 20% binder). The extrudate was then calcined, and the pore-forming reagent was split by heat treatment. An aqueous solution of ammonium heptamolybdate was then mixed with and impregnated on an extrudate to obtain a mordenite catalyst having 2% molybdenum uniformly distributed. A macropore volume of greater than about 50 nm for catalyst “I” was determined by mercury adsorption methods as 0.18 cm ³ / g.

Table 1 Catalyst Size and shape Hg vol. macropores (> 50 nm) ^(cm3 / g) X 1/12 ”cylinder 0.018 BUT 1/16 ”tripartite 0.132 AT 1/12 ”cylinder 0.255 FROM 1/12 ”cylinder 0.288 D 1/12 ”cylinder 0.280 E 1/12 ”cylinder 0.212 F 1/12 ”cylinder 0.281 G 1/16 ”tripartite 0.280 N 1/16 ”tripartite 0.01 I 1/16 ”tripartite 0.18

Pilot launch of the pilot plant

The performance of each catalyst was separately evaluated in an automated continuous mode on a fixed bed pilot plant. At each start-up, ten grams of the test catalyst was filled with a reactor, which mainly consisted of a pipe having an inlet and an outlet. The catalysts were pre-treated with flowing hydrogen for two hours at 750 ° F (400 ° C) and 200 psig (1.38 MPa) before the introduction of (liquid) feed. The feed consisted of a mixture of hydrogen and gaseous hydrocarbon in a 4: 1 molar ratio. Unless otherwise stated in this application, conditions in the reactor were set at a temperature of approximately 750 ° F (400 ° C) and a pressure of approximately 200 psig (1.38 MPa). The hourly average space velocity (WHSV) was either 4.0 or 6.0 (corresponding to a space velocity of the feed stream of approximately 40 grams per hour (g / h) and 60 g / h, respectively), as indicated in this application. Unless otherwise stated in this application, the catalysts were used under constant conditions for a minimum of three to five days before receiving product samples to ensure stable performance. Based on the fact that for the equilibrium reaction, first-order kinetics, the activity of the catalyst “X” (described above) was taken as 1.0.

Example 1

This example illustrates the performance capabilities of a catalyst with a lack of macropore volume (catalyst “X”) for the conversion of nitration grade toluene to a product containing xylene isomers. Separate launches were carried out with identical raw materials with WHSV 4.0 and with WHSV 6.0. The feed feed stream was a mixture of hydrogen and toluene (molar ratio of hydrogen: toluene 4: 1), and the conditions in the reactor were as described above. Analyzes of liquid raw materials (Raw materials,% wt.) And products (Product,% wt.) Obtained at each run are shown in Table 2 below.

table 2 Catalyst X Raw materials,% weight. Product,% weight. Whsv 4.0 6.0 Non-aromatic hydrocarbons 0.08 2.28 1.50 Benzene 0.00 15.73 12.81 Toluene 99.83 60.91 68.29 Ethylbenzene 0.05 0.18 0.13 p-xylene 0.02 4.38 3.71 m-xylene 0.03 9.49 8.00 o-xylene 0.00 4.16 3.49 Propylbenzene 0.00 0.00 0.00 Methyl ethylbenzene 0.00 0.27 0.22 Trimethylbenzene 0.00 2.33 1.66 A ₁₀₊ 0.00 0.26 0.18

The toluene conversion is determined by dividing the difference in the amount of toluene in the feed and in the product by the presence of toluene in the feed. For example, using data from a run with catalyst “X” and with WHSV 4.0, the toluene conversion was approximately 39.0 (that is, 39.0 = 100 × (99.83-60.91) ÷ 99.83). In contrast, using data from a run with catalyst “X” and WHSV 6.0, the toluene conversion was approximately 31.6 (that is, 31.6 = 100 × (99.83-68.29) ÷ 99.83).

The selectivity of any particular component in the product is determined by dividing the component yield by the toluene conversion. Thus, for example, using data from a run with catalyst “X” and WHSV 4.0, the selectivity of benzene was approximately 40.3% (i.e., 40.3 = 100 × (15.73 ÷ 39.0)), and the selectivity of xylene isomers was approximately 46.2% ( i.e., 46.2 = 100 × 18.3 ÷ 39.0)). In contrast, using data from a run with catalyst “X” and WHSV 6.0, the selectivity of benzene was approximately 40.5% (that is, 40.5 = 100 × (12.81 ÷ 31.6)), and the selectivity of xylene isomers was approximately 48.1% (that is, 48.1 = 100 × 15.2 ÷ 31.6)). Additionally, the selectivity of C ₉₊ aromatic hydrocarbons at WSHV 4.0 and 6.0 was 7.3% and 6.6%, respectively.

At WSHV 4.0, benzene is 15.7% and xylene isomers account for 18.0% (0.87 - weight ratio) as the main products. The presence of ethylbenzene in the product at WHSV 4.0 is approximately 0.99% by weight of C ₈ aromatic hydrocarbons, based on the total weight of C ₈ aromatic hydrocarbons. With WSHV 6.0, benzene is 12.8% and xylene isomers are 15.2% (0.84 - weight ratio) as the main products. The presence of ethylbenzene in the product at WHSV 6.0 is approximately 0.85% by weight of C ₈ aromatic hydrocarbons, based on the total weight of C ₈ aromatic hydrocarbons.

Example 2

This example illustrates the performance capabilities of a macropore-containing catalyst, catalyst “A”, for the conversion of nitration grade toluene to a product containing xylene isomers. Separate launches were carried out with almost identical raw materials with WHSV 4.0 and with WHSV 6.0. The feed stream was a mixture of hydrogen and toluene (molar ratio of hydrogen: toluene 4: 1), and the conditions in the reactor were as described above. Analyzes of liquid feed (Raw materials,% wt.) And products (Product,% wt.) Obtained at each run are shown in Table 3 below.

Table 3 Catalyst A Raw materials Product Raw materials Product Whsv 4.0 6.0 Non-aromatic hydrocarbons 0.08 0.66 0.08 0.57 Benzene 0.00 18.32 0.00 15.76 Toluene 99.82 55.90 99.81 61.90 Ethylbenzene 0.05 0.22 0.05 0.17 p-xylene 0.02 5.16 0.02 4.57 m-xylene 0.03 11.25 0.03 9.93 o-xylene 0.00 4.94 0.00 4.34 Propylbenzene 0.00 0.00 0.00 0.00 Methyl ethylbenzene 0.00 0.28 0.00 0.28 Trimethylbenzene 0.00 2.97 0.00 2.22 A ₁₀₊ 0.00 0.30 0.01 0.25

At WSHV 4.0, benzene is 18.3% and xylene isomers account for 21.4% (0.86 - weight ratio) as the main products. With WSHV 6.0, benzene is 15.8% and xylene isomers are 18.8% (0.84 - weight ratio) as the main products. Based on the obtained data, shown in Table 3, the toluene conversions at WSHV 4.0 and 6.0 were 44.0% and 38.0%, respectively. In contrast, the toluene conversions of similar feeds at WSHV 4.0 and 6.0 using catalysts “X” were 39.0% and 31.6%, respectively. Similarly, the selectivity of xylene isomers with catalyst “A” at WSHV 4.0 and 6.0 was 48.5% and 49.6%, respectively. In contrast, the selectivity of xylene isomers with catalyst “X” at WSHV 4.0 and 6.0 was 46.2% and 48.1%, respectively. The selectivity of benzene with catalyst “A” at WSHV 4.0 and 6.0 was 41.6% and 41.5%, respectively. In contrast, the selectivity of benzene with catalyst “X” at WSHV 4.0 and 6.0 was 40.3% and 40.5%, respectively. At both space velocities, toluene conversion, xylene selectivity and benzene selectivity were higher than toluene conversion, xylene selectivity and selectivity for benzene catalyst “X”, in which there were no macropores. Based on the kinetics of the first-order reversible equilibrium reaction, the relative activity of catalyst “A” is 1.38 times greater than the relative activity of catalyst “X”, in which there are no macropores.

Example 3

This example illustrates the performance capabilities of another catalyst containing macropores, catalyst “B,” to convert nitration grade toluene to a product containing xylene isomers. Separate launches were carried out with almost identical raw materials with WHSV 4.0 and with WHSV 6.0. The feed stream was a mixture of hydrogen and toluene (molar ratio of hydrogen: toluene 4: 1), and the conditions in the reactor were as described above. Analyzes of liquid feed (Raw materials,% wt.) And products (Product,% wt.) Obtained at each run are shown in Table 4 below.

Table 4 Catalyst B Raw materials Product Raw materials Product Whsv 4.0 6.0 Non-aromatic hydrocarbons 0.06 1.77 0.06 1.33 Benzene 0.00 19.57 0.00 16.49 Toluene 99.87 53.43 99.85 60.70 Ethylbenzene 0.03 0.17 0.03 0.14 p-xylene 0.01 5.17 0.01 4.54 m-xylene 0.02 11.25 0.02 9.96 o-xylene 0.00 4.97 0.00 4.30 Propylbenzene 0.00 0.00 0.00 0.00 Methyl ethylbenzene 0.00 0.22 0.00 0.21 Trimethylbenzene 0.00 3.16 0.00 2.24 A ₁₀₊ 0.00 0.29 0.02 0.20

With WSHV 4.0, benzene is 16.5% and xylene isomers are 18.7% (0.88 - weight ratio) as main products. With WSHV 6.0, benzene is 19.6% and xylene isomers make up 21.4% (0.92 - weight ratio) as the main products. Based on the data shown in Table 4, toluene conversions at WSHV 4.0 and 6.0 were 46.5% and 39.2%, respectively. In contrast, the toluene conversions of such feeds at WSHV 4.0 and 6.0 using catalyst “X” were 39.0% and 31.6%, respectively. At both space velocities, the conversion of toluene with catalyst “B” was higher than the conversion of toluene obtained with catalyst “X”, in which there were no macropores. Based on the kinetics of the first-order reversible equilibrium reaction, the relative activity of catalyst “B” turned out to be 1.43 times greater than the relative activity of catalyst “X”, in which there are no macropores.

At both space velocities, the conversion of toluene with catalyst “B” was higher than the conversion of toluene obtained with catalyst “X”, in which there were no macropores. Based on the kinetics of the first-order reversible equilibrium reaction, the relative activity of catalyst “B” turned out to be 1.43 times greater than the relative activity of catalyst “X”, in which there are no macropores.

The selectivity of xylene isomers with catalyst “B” at WSHV 4.0 and 6.0 was 46.0% and 47.7%, respectively. As shown in Example 1 above, the selectivity of xylene isomers with catalyst “X” at WSHV 4.0 and 6.0 was 46.2% and 48.1%, respectively.

This example demonstrates that a catalyst containing macropores has comparable selectivity at higher conversions. Thus, a catalyst containing macropores provides significantly greater activity without reducing selectivity for xylene (and benzene) isomers. The selectivity of benzene with catalyst “B” at WSHV 4.0 and 6.0 was 42.1% and 42.1%, respectively. In contrast, the selectivity of benzene with catalyst “X” at WSHV 4.0 and 6.0 was 40.3% and 40.5%, respectively.

Example 4

This example illustrates the performance capabilities of another catalyst containing macropores, catalyst “C,” to convert nitration grade toluene to a product containing xylene isomers. Separate launches were carried out with almost identical raw materials with WHSV 4.0 and with WHSV 6.0. The feed stream was a mixture of hydrogen and toluene (molar ratio of hydrogen: toluene 4: 1), and the conditions in the reactor were as described above. Analyzes of liquid feed (Raw materials,% wt.) And products (Product,% wt.) Obtained at each run are shown in Table 5 below.

Table 5 Catalyst "C" Raw materials Product Raw materials Product Whsv 4.0 6.0 Non-aromatic hydrocarbons 0.21 1.77 0.16 1.25 Benzene 0.00 19.50 0.00 16.78 Toluene 99.68 54.00 99.77 60.60 Ethylbenzene 0.03 0.24 0.03 0.17 p-xylene 0.01 5.07 0.01 4.50 m-xylene 0.02 11.04 0.02 9.75 o-xylene 0.00 4.84 0.00 4.26 Propylbenzene 0.00 0.01 0.00 0.01 Methyl ethylbenzene 0.00 0.33 0.00 0.27 Trimethylbenzene 0.00 3.01 0.00 2.25 A ₁₀₊ 0.04 0.24 0.01 0.18

At WSHV 4.0, benzene is 19.5% and xylene isomers account for 21.0% (0.93 - weight ratio) as the main products. At WSHV 6.0, benzene is 16.8% and xylene isomers account for 18.5% (0.91 - weight ratio) as the main products. Based on the data shown in Table 5, toluene conversions at WSHV 4.0 and 6.0 were 46.5% and 39.2%, respectively. In contrast, toluene conversions of similar feeds at WSHV 4.0 and 6.0 using catalyst “X” were 39.0% and 31.6%, respectively. At both space velocities, the toluene conversion was higher than the toluene conversion obtained with catalyst “X”, in which there were no macropores. Based on the kinetics of the first-order reversible equilibrium reaction, the relative activity of catalyst “C” turned out to be 1.42 times greater than the relative activity of catalyst “X”, in which there are no macropores.

The selectivity of xylene isomers with catalyst “C” at WSHV 4.0 and 6.0 was 45.7% and 47.2%, respectively. As shown in Example 1 above, the selectivity of xylene isomers with catalyst “X” at WSHV 4.0 and 6.0 was 46.2% and 48.1%, respectively. The selectivity of benzene with catalyst “C” at WSHV 4.0 and 6.0 was 42.6% and 42.7%, respectively. In contrast, the selectivity of benzene with catalyst “X” at WSHV 4.0 and 6.0 was 40.3% and 40.5%, respectively. This example demonstrates that a catalyst containing macropores has comparable selectivity at higher conversions. Thus, a catalyst containing macropores provides significantly greater activity without reducing selectivity for xylene (and benzene) isomers.

Example 5

This example illustrates the performance capabilities of yet another catalyst containing macropores, catalyst “D,” to convert nitration grade toluene to a product containing xylene isomers. One launch operation was carried out with raw materials with WHSV 6.0. The feed stream was a mixture of hydrogen and toluene (molar ratio of hydrogen: toluene 4: 1), and the conditions in the reactor were as described above. Analyzes of the liquid feed (Raw materials,% wt.) And the product (Product,% wt.) Obtained at startup are shown in Table 6 below.

Table 6. The catalyst "D" Raw materials Product Whsv 6.0 Non-aromatic hydrocarbons 0.07 1.19 Benzene 0.00 15.51 Toluene 99.68 62.29 Ethylbenzene 0.03 0.19 p-xylene 0.01 4.42 m-xylene 0.02 9.56 o-xylene 0.13 4.18 Propylbenzene 0.00 0.01 Methyl ethylbenzene 0.00 0.34 Trimethylbenzene 0.00 2.12 A ₁₀₊ 0.05 0.19

At WSHV 6.0, benzene is 15.5% and xylene isomers account for 18.2% (0.85 - weight ratio) as the main products. Based on the data shown in Table 6, the toluene conversion at WSHV 6.0 was 37.5%. In contrast, toluene conversions of similar feeds at WSHV 6.0 using catalyst “X” amounted to 31.6%. The toluene conversion was higher than the toluene conversion obtained with the catalyst “X”, in which there are no macropores. Based on the kinetics of the first-order reversible equilibrium reaction, the relative activity of the catalyst “D” turned out to be 1.38 times greater than the relative activity of the catalyst “X”, in which there are no macropores.

The selectivity of xylene isomers with catalyst “D” at WSHV 6.0 was 48.4%. In contrast, the selectivity of xylene isomers with catalyst “X” at WSHV 6.0 was 48.1%. The selectivity of benzene with catalyst “D” at WSHV 6.0 was 41.4%. As shown in Example 1 above, the selectivity of benzene with catalyst “X” at WSHV 6.0 was 40.5%. This example demonstrates that a catalyst containing macropores has comparable selectivity at higher conversions. Thus, a catalyst containing macropores provides significantly greater activity without reducing selectivity for xylene (and benzene).

Example 6

This example illustrates the performance capabilities of another catalyst containing macropores, catalyst “E”, to convert nitration grade toluene into a product containing xylene isomers. One launch operation was carried out with raw materials with WHSV 6.0. The feed stream was a mixture of hydrogen and toluene (molar ratio of hydrogen: toluene 4: 1), and the conditions in the reactor were as described above. Analyzes of liquid feed (Raw materials,% wt.) And product (Product,% wt.) Obtained at startup are shown in Table 7 below.

Table 7 Catalyst E Raw materials Product Whsv 6.0 Non-aromatic hydrocarbons 0.25 0.85 Benzene 0.00 13.69 Toluene 99.68 67.69 Ethyl benzene 0.03 0.14 p-xylene 0.01 3.83 m-xylene 0.03 8.24 o-xylene 0.00 3.60 Propylbenzene 0.00 0.01 Methyl ethylbenzene 0.00 0.28 Trimethylbenzene 0.00 1.55 A ₁₀₊ 0.00 0.12

The toluene conversion was higher than the toluene conversion obtained with the catalyst “X”, in which there are no macropores. Based on the kinetics of the first-order reversible equilibrium reaction, the relative activity of the catalyst “E” turned out to be 1.15 times greater than the relative activity of the catalyst “X”, in which there are no macropores. The catalyst “E” shows improved activity with respect to the catalyst “X” even in that the catalyst “E” contains only 70% H-mordenite compared to the catalyst “X”, which has 80% H-mordenite. With WSHV 6.0, benzene is 13.7% and xylene isomers are 15.7% (0.87 - weight ratio) as the main products. Based on the data shown in Table 7, the toluene conversion at WSHV 6.0 was 32.1%. On the contrary, the conversion of toluene of such raw materials at WSHV 6.0 using catalysts “X” was 31.6%.

The selectivity of xylene isomers with catalyst “E” at WSHV 6.0 was 42.8%. In contrast, the selectivity of xylene isomers with catalyst “X” at WSHV 6.0 was 48.1%. The selectivity of benzene with catalyst “E” at WSHV 6.0 was 42.7%. As shown in Example 1 above, the selectivity of benzene with catalyst “X” at WSHV 6.0 was 40.5%. This example demonstrates that a catalyst containing macropores has comparable selectivity at higher conversions. Thus, a catalyst containing macropores provides significantly greater activity without reducing selectivity for xylene (and benzene).

Example 7

This example illustrates the performance capabilities of another catalyst containing macropores, catalyst “F”, to convert nitration grade toluene into a product containing xylene isomers. One launch operation was carried out with raw materials with WHSV 6.0. The feed stream was a mixture of hydrogen and toluene (molar ratio of hydrogen: toluene 4: 1), and the conditions in the reactor were as described above. Analyzes of liquid feed (Raw materials,% wt.) And product (Product,% wt.) Obtained at startup are shown in Table 8 below.

Table 8 Catalyst ”F” Raw materials Product Whsv 6.0 Non-aromatic hydrocarbons 0.07 1.15 Benzene 0.00 16.36 Toluene 99.70 61.76 Ethylbenzene 0.03 0.20 p-xylene 0.01 4.36 m-xylene 0.02 9.42 o-xylene 0.16 4.12 Propylbenzene 0.00 0.01 Methyl ethylbenzene 0.00 0.34 Trimethylbenzene 0.00 2.13 A ₁₀₊ 0.00 0.16

With WSHV 6.0, benzene is 16.4% and xylene isomers make up 17.9% (0.92 - weight ratio) as the main products. Based on the data obtained are shown in Table 8, the toluene conversion at WSHV 6.0 was 38.1%. On the contrary, the conversion of toluene of such raw materials at WSHV 6.0 using catalyst "X" was 31.6%. The toluene conversion was higher than the toluene conversion obtained on the catalyst "X", in which there are no macropores. Based on the kinetics of the first-order reversible equilibrium reaction, the relative activity of the catalyst “F” turned out to be 1.38 times greater than the relative activity of the catalyst “X”, in which there are no macropores.

The selectivity of xylene isomers on catalyst “F” at WSHV 6.0 was 47.0%. In contrast, the selectivity of xylene isomers with catalyst “X” at WSHV 6.0 was 48.1%. The benzene selectivity on catalyst “F” at WSHV 6.0 was 43.0%. In contrast, the selectivity of benzene on catalyst “X” at WSHV 6.0 was 40.5%.

Example 8

This example illustrates the performance capabilities of another macropore-containing catalyst, catalyst “G,” to convert nitration grade toluene to a product containing xylene isomers. Separate launches were carried out with almost identical raw materials with WHSV 4.0 and with WHSV 6.0. The feed stream was a mixture of hydrogen and toluene (molar ratio of hydrogen: toluene 4: 1), and the conditions in the reactor were as described above. Analyzes of liquid feed (Raw materials,% wt.) And products (Product,% wt.) Obtained at each run are shown in Table 9 below.

Table 9 Catalyst "G" Raw materials Product Raw materials Product Whsv 4.0 6.0 Non-aromatic hydrocarbon 0.08 1.74 0.08 1.17 Benzene 0.00 20.00 0.00 16.95 Toluene 99.64 52.69 99.63 59.37 Ethylbenzene 0.03 0.31 0.03 0.22 p-xylene 0.01 5.17 0.01 4.69 m-xylene 0.02 11.25 0.02 10.17 o-xylene 0.17 4.95 0.16 4.46 Propylbenzene 0.00 0.01 0.00 0.01 Methyl ethylbenzene 0.00 0.43 0.00 0.38 Trimethylbenzene 0.00 3.14 0.00 2.35 A ₁₀₊ 0.05 0.32 0.06 0.23

At WSHV 4.0, benzene is 20.0% and xylene isomers account for 21.4% (0.93 - weight ratio) as the main products. With WSHV 6.0, benzene is 17.0% and xylene isomers are 19.3% (0.88 - weight ratio) as main products. Based on the data shown in Table 9, toluene conversions at WSHV 4.0 and 6.0 were 47% and 40%, respectively. In contrast, the toluene conversions of such feeds at WSHV 4.0 and 6.0 using catalyst “X” were 39.0% and 31.6%, respectively. At both space velocities, the toluene conversion was higher than the toluene conversion on the “X” catalyst, in which there were no macropores. Based on the kinetics of the first-order reversible equilibrium reaction, the relative activity of the catalyst “G” turned out to be 1.48 times greater than the relative activity of the catalyst “X”, in which there are no macropores.

The selectivity of xylene isomers on the “G” catalyst at WSHV 4.0 and 6.0 was 45.5% and 48.3%, respectively. As shown in Example 1 above, the selectivity of xylene isomers on the “X” catalyst with WSHV 4.0 and 6.0 was 46.2% and 48.1%, respectively. The benzene selectivity on the “G” catalyst at WSHV 4.0 and 6.0 was 42.5% and 42.4%, respectively. As shown in Example 1 above, the benzene selectivity on the “X” catalyst with WSHV 4.0 and 6.0 was 40.3% and 40.5%, respectively. This example demonstrates that a catalyst containing macropores has comparable selectivity at higher conversions. Thus, a catalyst containing macropores provides significantly greater activity without reducing selectivity for xylene (and benzene).

Table 10 below summarizes the properties of the catalyst and the relative activities of the catalysts “X” and from “A” to “G.” As noted above, all catalysts “X” and from “A” to “G” contained 80% H- mordenite, except that the “E” catalyst contained only 70% H-mordenite, despite this, and as indicated below, the “E” catalyst provides improved activity compared to the “X” catalyst.

Table 10 Catalyst Size and
The form Relative activity Hg Macropore volume (50-100 nm) (cm ³ / g) X 1/12 "cylinder 1.00 0.018 BUT 1/16 "tripartite 1.38 0.132 AT 1/12 "cylinder 1.43 0.255 FROM 1/12 "cylinder 1.42 0.288 D 1/12 "cylinder 1.38 0.280 E 1/12 "cylinder 1.15 0.212 F 1/12 "cylinder 1.38 0.281 G 1/16 " 1.48 0.280 tripartite

Moreover, 1/12-inch cylindrical extrudates of more than about 0.2 cm ³ / g are required to give the highest activity. For example, there is an advantage in activity (1.15 times higher) when increasing the volume of macropores to 0.212 cm ³ / g (catalyst “E”) compared to catalyst “X.” However, for catalysts with a volume of macropores of more than 0.25 cm ³ / g activity increases to a maximum of approximately 1.4 (catalysts "B", "C", "D" and "F"). For smaller extrudates, lower macropore volume values may give acceptable activity. For example, if the extrudate size is reduced to 1/16 inch, and the shape is chosen to obtain an even smaller effective size (catalyst “A”), a catalyst with a maximum activity of about 1.4 will be achieved with a macropore volume of 0.13 cm ³ / g. The size of the macropores, therefore, depends on the size of the extrudate and most preferred is significant from about 0.1 to 0.3 cm ³ / g Macropore volumes above about 0.02 cm ³ / g, however, lead to catalysts with higher relative activity.

Example 9

This example compares the performance capabilities of a catalyst with a lack of macropores (catalyst “H”) compared with a catalyst containing macropores (catalyst “I”) to convert nitration grade toluene to a product containing xylene isomers. Separate starts with each catalyst were carried out with almost identical raw materials at WHSV 6.0. The feed stream was a mixture of hydrogen and toluene (molar ratio of hydrogen: toluene 4: 1), and the conditions in the reactor were as described above. Analyzes of liquid raw materials (Raw materials,% wt.) And products (Product,% wt.) Obtained on each catalyst in the following days, and conversion analysis are presented in Table 11 (catalyst “H”) and Table 12 (catalyst “I”) given below:

Table 11 The catalyst ”N” Raw materials Product
Day 1 Product
Day 2 Non-aromatic hydrocarbons 0.09 1.48 1.21 Benzene 0.00 11.92 9.90 Toluene 99.83 70.69 75.83 Ethylbenzene (EB) 0.04 0.12 0.09 p-xylene 0.01 3.50 2.91 m-xylene 0.02 7.50 6.21 o-xylene 0.00 3.25 2.71 Propylbenzene 0.00 0.00 0.00 Methyl ethylbenzene 0.00 0.26 0.23 Trimethylbenzene 0.00 1.11 0.78 A ₁₀₊ 0.00 1.17 0.13 Benzene / Xylenes 0.84 0.84 Toluene conversion 29.19 04/24 Ethylbenzene selectivity in C ₈ fraction 0.84 0.75 Selectivity for C ₉ aromatic hydrocarbons 5.29 4.73

Table 12 The catalyst "I" Raw materials Product
Day 1 Product
Day 2 Product
Day 3 Non-aromatic hydrocarbons 0.09 0.70 0.70 0.70 Benzene 0.02 18.55 19.20 19.40 Toluene 99.79 55.50 55.01 55.10 Ethylbenzene (EB) 0.04 0.19 0.17 0.17 p-xylene 0.02 5.24 5.21 5.16 m-xylene 0.04 11.35 11.29 11.18 o-xylene 0.00 4.95 4.93 4.88 Propylbenzene 0.00 0.01 0.01 0.00 Methyl ethylbenzene 0.01 0.27 0.24 0.23 Trimethylbenzene 0.01 3.01 3.02 2.96 A ₁₀₊ 0.00 0.23 0.22 0.21 Benzene / Xylenes 0.86 0.90 0.92 Toluene conversion 44.37 44.86 44.76 Ethylbenzene selectivity in C ₈ fraction 0.90 0.81 0.78 Selectivity for C ₉ aromatic hydrocarbons 7.90 7.74 7.57

Based on previous data, the macropore-free catalyst, catalyst “H,” had a low toluene conversion (24% on day 1 and 29% on day 2) when compared to the toluene conversion achieved on catalyst “I” (sequentially approximately 44% each day), which contains a volume of macropores. Additionally, it was observed that the catalyst "I" provided stable performance (that is, there was no loss of activity), while the catalyst "H" did not provide equally stable performance, losing 5% conversion of toluene after 1-2 days. Thus, the preceding example demonstrates that a catalyst containing a macropore volume is more stable than a catalyst with a lack of macropore volume.

Example 10

This example demonstrates the ability of catalyst “C” (a macroporous catalyst) to convert raw materials containing toluene, benzene and some light non-aromatic hydrocarbons into xylene isomers. Three almost identical feeds were converted on a catalyst. At three starts, the reaction conditions were identical, except that the temperature of the reactor and WHSV were different.

Analyzes of liquid raw materials (Raw materials,% wt.), The obtained product (Product,% wt.) And conversion are presented in Table 13 below.

Table 13 The catalyst "C" Raw materials Product Raw materials Product Raw materials Product Whsv 0.5 2.0 3.0 Non-aromatic hydrocarbons 3.05 3.58 3.61 6.04 3.05 3.84 Benzene 7.59 21.71 5.91 20.72 7.64 19.86 Toluene 82.89 49.38 79.76 45.43 82.85 09/09 Ethylbenzene 1.00 0.84 2.07 0.68 1.00 0.52 p-xylene 1.77 4.90 2.88 5.32 1.77 4.30 m-xylene 3.29 10.78 5.26 11.68 3.28 9.35 o-xylene 0.42 4.48 0.52 5.02 0.41 4.08 Propylbenzene 0.00 0.02 0.00 0.01 0.00 0.01 Methyl ethylbenzene 0.00 0.96 0.00 0.74 0.00 0.59 Trimethylbenzene 0.00 2.94 0.00 3.80 0.00 2.14 A ₁₀₊ 0.00 0.42 0.00 0.56 0.00 0.22 Reactor Pressure (psig) 200 200 200 Reactor Temperature (° F) 750 720 750 Benzene / Xylenes 0.96 1.11 1.00 Toluene conversion 40.43 43.04 33.50 Ethylbenzene selectivity in C ₈ fraction 3.98 3.00 2.84 Selectivity for C ₉ aromatic hydrocarbons 10.73 11.88 8.84

When WHSV was 0.5, the pure benzene obtained in the conversion product was 14.12, while the final xylene isomers obtained in the conversion product were 14.68. Accordingly, the ratio of pure benzene to pure xylene isomers (Benzene / Xylenes) obtained by the conversion of this toluene feedstock is 0.96 (i.e., 0.96 = (14.12 ÷ 14.68)). This ratio is given in the preceding table as Benzene / Xylenes. The data in the preceding table also shows that when temperature and pressure remain constant (750 ° F and 200 psig) and WHSV is increased (from 0.5 to 3.0), then toluene conversion, selectivity of ethylbenzene in fraction C ₈ and selectivity to aromatic hydrocarbons C _{9 are} decreasing. The decrease in toluene conversion with an increase in WHSV is the expected reaction because, since more feed is passed through the catalyst in a certain amount of time, more load is placed on the catalyst, resulting in less conversion. Typically, toluene conversion will depend on temperature, pressure and WHSV, WHSV is a combination of the amount of catalyst and feed rate.

This example also demonstrates that said catalyst is capable of converting raw materials, obtaining an increase in the purity of xylene isomers, and providing a decrease in pure ethylbenzene. Not wishing to dwell on any particular theory, it is believed that the ethyl group on ethylbenzene is removed using a catalyst and then saturated with a catalyst hydrogenation component (molybdenum in this catalyst) to obtain ethane, which is non-reactive. The absence of a hydrogenation component would likely leave a reactive ethyl group in the product mixture that could undesirably react with the desired component in the mixture.

As a rule, a specialist skilled in this technology would not attempt (or expect) to convert non-aromatic hydrocarbons (e.g. paraffins) with a traditional catalyst, because such a feed would be very harmful to the catalyst. Specifically, non-aromatic hydrocarbons react in the presence of a conventional catalyst, resulting in products that will rapidly deactivate the catalyst and alter the selectivity of the catalyst. Instead, a qualified person would direct such raw materials to expensive operations to extract non-aromatic hydrocarbons from the raw materials before attempting to convert the raw materials.

The preceding example demonstrates that the disclosed macroporous catalyst can be used to convert feeds containing at least about 3% by weight of non-aromatic hydrocarbons without suffering from the disadvantages inherent in conventional catalysts. In addition, the ability to convert such raw materials eliminates the need for extraction of non-aromatic hydrocarbons before the conversion, which gives significant savings in operating costs.

It was also found that benzene obtained by the conversion of this macroporous catalyst with this impregnated molybdenum has a purity acceptable for the processing industry (i.e., less than 0.1% of benzene is actually saturated). This is an unexpected benefit. Although such purity could be obtained using a non-metallic impregnated catalyst, the feed is toluene and should not contain non-aromatic hydrocarbons. If non-aromatic hydrocarbons were present, then a qualified specialist would impregnate the catalyst with platinum or nickel. Thus, benzene in the conversion product would be unacceptable for the processing industry, which requires a benzene purity of at least 99.9%.

Example 11

This example demonstrates the ability of the catalyst “G” (macroporous catalyst) to convert raw materials containing toluene, benzene and some light non-aromatic hydrocarbons into xylene isomers. Analyzes of liquid raw materials (Raw materials,% wt.), The obtained product (Product,% wt.) And conversion are presented in Table 14 below.

Table 14 The catalyst "G" Raw materials Product Whsv 5.9 Non-aromatic hydrocarbons 3.76 4.88 Benzene 5.40 18.77 Toluene 79.52 50.32 Ethylbenzene 2.19 0.61 p-xylene 3.03 5.15 m-xylene 5.52 11.18 o-xylene 0.55 4.95 Propylbenzene 0.00 0.01 Methyl ethylbenzene 0.00 0.66 Trimethylbenzene 0.01 3.14 A ₁₀₊ 0.02 0.33 Reactor Pressure (psig) 200 Reactor Temperature (° F) 780 Benzene / Xylenes 1.10 Toluene conversion 36.73 Ethylbenzene selectivity in C ₈ fraction 2.79 Selectivity for C ₉ aromatic hydrocarbons 11.21

Examples 2-8 above showed that a macroporous catalyst impregnated with molybdenum can be used to convert nitration grade toluene, while Example 10 and this example demonstrate the ability of such a catalyst to convert toluene containing previously undesirable non-aromatic hydrocarbons. The flexibility of the process provided by the catalyst, and this method is a great advantage for the engineer, as it eliminates the need for process modifications that depend on the exact composition of the feed feed, toluene, and make it possible to obtain xylene isomers, as well as benzene used.

Example 12

This example demonstrates the ability of catalyst "C" (macroporous catalyst) to convert a feed containing C ₉₊ aromatic hydrocarbons into xylene isomers. Analyzes of liquid raw materials (Raw materials,% wt.), The obtained product (Product,% wt.) And conversion are presented in Table 15 below.

Table 15 The catalyst "C" Raw materials Product Whsv 1.0 Non-aromatic hydrocarbons 0.85 20.59 Benzene 0.09 4.45 Toluene 0.24 16.17 Ethylbenzene 0.00 5.95 p-xylene 0.01 4.98 m-xylene 0.02 10.97 o-xylene 0.50 4.65 Propylbenzene 0.17 0.00 Methyl ethylbenzene 17.16 10.64 Trimethylbenzene 18.24 9.75 A ₁₀₊ 62.73 11.83 Reactor Pressure (psig) 200 Reactor Temperature (° F) 680 Benzene / Xylenes 0.22 Toluene yield 15.94 Ethylbenzene selectivity in C ₈ fraction 22.40 Conversion With ₈₊ Aromatic Carbons 67.20

This example demonstrates that using the method it is possible to convert raw materials containing C ₉₊ aromatic hydrocarbons. Previously, a specialist qualified in this technology would not have made an attempt (or would have expected) to convert raw materials on a traditional catalyst, because C ₁₀₊ aromatic hydrocarbons quickly deactivate the catalyst. Thus, a qualified person would fractionate the feed to remove C ₁₀₊ aromatic hydrocarbons before attempting conversion on a conventional catalyst. This example, however, demonstrates that a macroporous catalyst impregnated with a hydrogenation component can be used to convert a feed containing C ₉₊ aromatic hydrocarbons, thus useful in eliminating the fractionation step.

This is important because C ₁₀₊ aromatic hydrocarbons are often present in the conversion product. See, for example, Examples 1-11 above. As noted above, such a product cannot be further converted on a conventional catalyst due to the deactivation effect of the C ₁₀₊ catalyst with aromatic hydrocarbons. However, because such deactivation is not a problem for the catalyst disclosed in this application, and because such C ₁₀₊ aromatic hydrocarbons can be converted on the catalyst, raw materials containing C ₁₀₊ aromatic hydrocarbons can be recycled with fresh raw materials without the need for recycling fractionation. to remove such C ₁₀₊ aromatic hydrocarbons.

Example 13

This example demonstrates the ability of the catalyst “G” (macroporous catalyst) to convert raw materials containing C ₉₊ aromatic hydrocarbons into xylene isomers. Five almost identical types of raw materials were converted on the catalyst. At five starts, the reaction conditions were identical, except that the temperature of the reactor was changed at each start. Analyzes of liquid raw materials (Raw materials,% wt.), The obtained product (Product,% wt.) And conversion are presented in Table 16 below.

Example 14

This example demonstrates the ability of the “D” catalyst (macroporous catalyst) to convert a feed containing C ₉₊ aromatic hydrocarbons (and mainly C ₉ aromatic hydrocarbons) to xylene isomers. Analyzes of liquid raw materials (Raw materials,% wt.), The obtained product (Product,% wt.) And conversion are presented in Table 17 below.

Table 17 The catalyst "D" Raw materials Product Whsv 2.0 Non-aromatic hydrocarbons 0.20 12.21 Benzene 0.12 4.74 Toluene 0.07 06/23 Ethylbenzene 0.00 0.62 p-xylene 0.01 8.45 m-xylene 0.02 18.48 o-xylene 0.10 8.11 Propylbenzene 6.67 0.00 Methyl ethylbenzene 49.66 1.46 Trimethylbenzene 42.28 05/19 A ₁₀₊ 0.88 3.83 Reactor Pressure (psig) 200 Reactor Temperature (° F) 750 Benzene / Xylenes 0.13 Toluene yield 22.99 Ethylbenzene selectivity in C ₈ fraction 1.75 Conversion of C ₉₊ Aromatic Hydrocarbons 75.54

Example 15

This example demonstrates the ability of catalyst "C" (macroporous catalyst) to convert a feed containing C ₉₊ aromatic hydrocarbons (and mainly C ₉ aromatic hydrocarbons) to xylene isomers. Six almost identical types of raw materials were converted on a catalyst. At six starts, the reaction conditions were identical, except that the temperature of the reactor was changed at each start. Analyzes of liquid raw materials (Raw materials,% wt.), The obtained product (Product,% wt.) And conversion are presented in Table 18 below.

When the obtained xylene isomers undergo further hydrocarbon processing after the conversion operation to produce para-xylene, the ethylbenzene present in the C ₈ aromatic hydrocarbon fraction must be converted to benzene by dealkylation (deethylation). Such elimination of ethyl groups requires the passage of a fraction through another catalyst to remove the ethyl group from ethylbenzene. This elimination of ethyl groups can decompose a portion of the xylene isomers present in the C ₈ aromatic hydrocarbon fraction, ultimately resulting in a loss in yield of xylene isomers. Based on the data below, the low selectivity of ethylbenzene in the C ₈ aromatic hydrocarbon fraction is achievable by the demonstrated method. Such a low ethylbenzene content is desirable because it reduces the cost of further hydrocarbon processing and improves the yield of xylene in petrochemical processes for producing para-xylene.

Based on previous data, at constant pressure and WHSV, the toluene yield and the conversion of C ₉₊ aromatic hydrocarbons increase with increasing temperature. Similarly, at constant pressure and WHSV, the selectivity of ethylbenzene in the C ₈ aromatic hydrocarbon fraction decreases with increasing temperature.

Example 16

This example demonstrates the ability of catalyst "D" (macroporous catalyst) to convert a feed containing C ₉ aromatic hydrocarbons and toluene into xylene isomers. Analyzes of liquid feed (Raw materials,% wt.), The obtained product (Product,% wt.) And conversion are presented in Table 19 below.

Table 19 The catalyst "D" Raw materials Product Whsv 1.0 Non-aromatic hydrocarbons 0.19 6.53 Benzene 0.01 9.50 Toluene 49.29 36.55 Ethylbenzene 0.02 2.09 p-xylene 0.02 7.03 m-xylene 0.04 15.36 o-xylene 0.06 6.78 Propylbenzene 3.33 0.00 Methyl ethylbenzene 04/25 3.78 Trimethylbenzene 21.50 10.03 A ₁₀₊ 0.50 2.34 Reactor Pressure (psig) 200 Reactor Temperature (° F) 680 Benzene / Xylenes 0.33 Toluene conversion 25.85 Ethylbenzene selectivity in C ₈ fraction 6.69 Conversion With ₉₊ Aromatic Hydrocarbons 67.92

This example also demonstrates the preparation of C ₉₊ aromatic hydrocarbons, which in accordance with the preceding examples (for example, Examples 12 and 13) can be recycled back to the feed for further conversion on the same type of catalyst. This example further demonstrates the flexibility of a process capable of performing various operations with raw materials using the same overall process configuration, removing products of a particular conversion that are desired.

Example 17

This example demonstrates the ability of catalyst "G" to convert a feed containing C ₉₊ aromatic hydrocarbons, benzene and toluene into xylene isomers. Five almost identical types of feed were converted on the catalyst. Such a feed is representative of a feed containing recycling, and, as explained above, the advantages of the method using a macroporous catalyst impregnated with a hydrogenation component include its ability to convert such feed, without requiring complicated and costly purification of the product from the previous oil refining process and subsequent processing hydrocarbons.

At five starts, the reaction conditions were identical, except that the temperature of the reactor was changed at each start. Analyzes of liquid feed (Raw materials,% wt.), The obtained product (Product,% wt.) And conversion are presented in Table 20 below.

Table 20 The catalyst "G" Raw materials About
duct Raw materials About
duct Cheeses About
duct Raw materials About
duct Raw materials About
duct Whsv 1.3 1.3 1.3 1.3 1.3 Non-aromatic hydrocarbons 2.14 10.72 2.17 13.15 2.14 14.97 2.15 16.61 2.58 17.35 Benzene 4.45 14.40 4.37 15.80 4.33 16.60 4.22 17.16 4.32 16.88 Toluene 49.07 35.96 48.85 36.44 48.93 36.07 48.61 35.84 50.75 35.52 Ethylbenzene 0.59 3.89 0.59 2.05 0.59 0.99 0.59 0.45 0.62 0.28 p-xylene 1.04 5.60 1.05 5.73 1.05 5.74 1.05 5.62 1.10 5.63 m-xylene 1.94 12.31 1.94 12.59 1.95 12.59 1.95 12.31 2.04 12.30 o-xylene 0.45 5.26 0.45 5.43 0.45 5.52 0.45 5.44 0.47 5.49 Propylbenzene 0.09 0.00 0.09 0.01 0.09 0.01 0.09 0.01 0.09 0.01 Methyl ethylbenzene 7.19 4.50 7.23 2.19 7.22 1.04 7.27 0.47 7.59 0.30 Trimethylbenzene 7.57 5.43 7.61 5.52 7.62 5.69 7.66 5.52 8.15 5.58 A ₁₀₊ 25.47 1.93 25.67 1.09 25.63 0.76 25.97 0.57 22.29 0.65 Pressure in the reactor (psig) 200 200 200 200 200 Reactor Temperature (° F) 700 725 750 775 800 Benzene / Xylenes 0.50 0.56 0.60 0.65 0.63 Toluene Conversion 26.72 25.40 26.28 26.27 30.00 Ethylbenzene selectivity in C ₈ fraction 14.36 7.96 3.98 1.89 1.18 The conversion of C ₉₊ aromatic hydrocarbons 70.59 78.30 81.51 83.96 82.85

Based on the previous data, at constant pressure and WHSV, the conversion of C ₉₊ aromatic hydrocarbons increases in the same way as the temperature increases. Similarly, at constant pressure and WHSV, the selectivity of ethylbenzene in the C ₈ aromatic hydrocarbon fraction decreases as the temperature increases. Toluene conversion, however, does not change significantly in response to temperature changes when the pressure and WHSV remain constant.

Claims (8)

1. A method of producing xylene isomers, comprising contacting a feed containing C ₉ aromatic hydrocarbons on a non-sulfidated catalyst having a macropore volume of from about 0.02 to about 0.5 cm ³ / g, the catalyst comprising a carrier impregnated with a hydrogenation component representing is a group VIB metal or its oxide, the carrier comprises a macroporous binder with pore sizes of more than 500 Å and a large-pore sieve with pore sizes of at least 6 Å, at an hourly average feed rate of 0.1 to 30, pressure apart from 0.17 to 6.9 MPa or more, a temperature of 200 to 800 ° C. 2. The method according to claim 1, characterized in that the sieve is selected from the group consisting of large-pore zeolites, large-pore aluminophosphates, large-pore silicoaluminophosphates and mixtures thereof. 3. The method according to claim 2, characterized in that the large-pore zeolite is selected from the group consisting of mordenite, beta zeolite, Y-zeolite and mixtures thereof. 4. A method of producing xylene isomers, comprising contacting a feed containing C ₆ -C ₈ aromatic hydrocarbons on a non-sulfidated catalyst having a macropore volume of from about 0.02 to about 0.5 cm ³ / g, the catalyst comprising a carrier impregnated with a component the hydrogenation, which is a metal of group VIB or its oxide, the carrier includes a macroporous binder with pore sizes of more than 500 Å and a sieve selected from the group consisting of sieves with pores from 4 to 6 Å, sieves with pores of at least 6 Å and mixtures thereof, at an hourly average feed rate of 0.1 to 30, a pressure of 0.17 to 6.9 MPa or more, and a temperature of 200 to 800 ° C. 5. The method according to claim 4, characterized in that the sieve with a pore size of 4 to 6 Å is selected from the group consisting of zeolites, aluminophosphates, silicoaluminophosphates and mixtures thereof. 6. The method according to claim 5, characterized in that the zeolite with a pore size of 4 to 6 Å is selected from the group consisting of aluminophosphate-eleven (AEL), Edinburgh University-one (EUO), ferrierite (FER), Mobile-eleven (MEL), Mobile-fifty-seven (MP8), Mobile-five (MFI), Mobile-twenty-three (MTT), new-eighty-seven (NES), theta-one (TON) and mixtures thereof. 7. The method according to claim 4, characterized in that the macroporous binder is selected from the group consisting of alumina, aluminum phosphates, clays, silica-alumina, silica, silicates, titanium dioxide, zirconia and mixtures thereof. 8. The method according to claim 4, further comprising separating at least a portion of the xylene isomers from the product and recycling back to the raw portion of the product depleted in xylene isomers.